Social Exchange Theory (SET), originally introduced by Homans (1958) and further developed by Blau (1964), provides the theoretical underpinning for this study. The theory asserts that social behavior is the result of an exchange process, where individuals seek to maximize benefits while minimizing costs. In organizational contexts, SET explains why employees reciprocate favorable organizational treatment—such as fairness or developmental support—with loyalty, engagement, and performance (Cropanzano & Mitchell, 2005). This reciprocal process is anchored in the perceived balance of benefit and obligation. SET also emphasizes the role of trust, mutual dependence, and relational norms in sustaining long-term interactions, making it especially relevant in high- demand environments like the EPC industry. Particularly relevant is the role of Perceived Organizational Support (POS) as the cognitive-emotional interpretation of these exchanges. POS represents the extent to which employees believe their organization values their contributions and supports their well- being (Rhoades & Eisenberger, 2002). In this research, SET frames the relationships between Career Development (X1) and Organizational Justice (X2) with Sustainable Engagement (Y), with POS functioning as a mediating construct

that reflects employees' interpretation of organizational care and reciprocity.

Sustainable Engagement (SE) is defined as the consistent, meaningful, and long-term involvement of employees in their work, aligning individual energy with organizational sustainability goals. Rooted in Kahn (1990) concept of personal engagement—where employees physically, emotionally, and cognitively immerse themselves in their roles—SE was further conceptualized by Ogueyungbo et al. (2022) into three core dimensions: Affective Engagement, which refers to emotional connection, enthusiasm, and sense of purpose in one’s work (Jiatong et al., 2022); Behavioral Engagement, which reflects discretionary effort, initiative-taking, and persistence beyond formal job requirements (Ogueyungbo et al., 2022); Cognitive Engagement, which involves psychological presence, creativity, and deep mental focus in problem-solving (Gürbüz et al., 2023; Saks, 2019).

Unlike temporary motivation or task compliance, SE reflects a deeper investment in work that is sustainable over time. It is a strategic construct that bridges employee well-being with organizational adaptability, often fostered through managerial fairness, developmental support, and perceived care. Thus, identifying its antecedents—such as CD, OJ, and POS—becomes critical for ensuring long-term organizational performance.

Career Development (CD) refers to structured organizational efforts to promote employee growth through skill enhancement, promotion pathways, and continuous performance improvement. As defined by Busro (in Sinaga et al., 2022), CD encompasses three dimensions: career provision (e.g., opportunity clarity), self-improvement (e.g., training and education), and quality enhancement (e.g., discipline and motivation).

Within the SET framework, CD acts as a valuable organizational input. Employees who perceive tangible career support often interpret it as a sign of respect and investment, prompting them to respond with sustained engagement. Prior research confirms that structured career advancement enhances commitment and motivation, particularly when aligned with personal aspirations (Jena & Nayak, 2023; Jia-jun & Hua-ming, 2022).

Building on these perspectives, CD contributes not only to individual development but also to the organization’s long-term talent sustainability. Rachman & Iqbal (2025) found that well-structured development opportunities enhance job satisfaction and reduce turnover intention. Likewise, Haliansyah et al. (2024) confirmed that career development significantly strengthens employee commitment when aligned with personal growth needs. Such findings reinforce the notion that CD is a strategic resource, capable of generating reciprocal commitment and sustainable engagement, particularly in dynamic project-based environments like EPC firms.

H1: Career Development has a significant positive effect on Sustainable Engagement.

Organizational Justice (OJ) refers to employees’ perception of fairness within the organization. It comprises four dimensions as proposed by Colquitt et al. (2019): distributive justice (fairness of outcomes), procedural justice (fairness of processes), interpersonal justice (respect and dignity), and informational justice (transparency and adequacy of communication).

Fair treatment signals ethical conduct and promotes psychological safety, which encourages emotional attachment and long-term commitment. In SET terms, justice is a social currency that organizations offer, which employees reciprocate through proactive behavior, loyalty, and cognitive involvement (Pakpahan et al., 2020; Na’imah et al., 2022). When employees feel fairly treated, they are more likely to engage beyond minimum requirements.

Extending this perspective, empirical studies highlight the direct and indirect roles of OJ in fostering employee engagement. Aggarwal et al. (2022) found that distributive and procedural justice enhance engagement and reduce turnover intentions. Deepa (2020) highlighted that all justice dimensions positively affect emotional, cognitive, and physical engagement. Similarly, Mubashar et al. (2022) showed that organizational justice fosters engagement through organizational trust. These findings suggest that fair treatment, transparent communication, and respectful interactions are essential in promoting sustained engagement, especially in industries where employees often operate under high demands.

H2: Organizational Justice has a significant positive effect on Sustainable Engagement.

Perceived Organizational Support (POS) refers to employees’ belief that the organization values their contributions and genuinely cares for their well- being (Eisenberger et al., 1986). In this study, POS is conceptualized through three dimensions: supervisor support, job conditions and rewards, and organizational fairness (Azizah & Rokhman, 2021). These dimensions capture both instrumental and emotional aspects of support, forming a strong psychological climate that fosters reciprocal behavior.

According to Social Exchange Theory (SET), POS functions as a key interpretive mechanism that transforms organizational actions into individual outcomes. When employees receive signals of support—through fair treatment and developmental opportunities—they internalize these actions as trust- building gestures and respond with higher engagement (Sun, 2019; Alshaabani et al., 2021). Thus, POS is not only a product of favorable organizational practices but also a driver of positive employee attitudes and behaviors.

Career Development (CD) and Organizational Justice (OJ) both play essential roles in shaping POS. Developmental opportunities such as training, career planning, and personal improvement initiatives signal organizational investment in employee growth (Jia-jun & Hua-ming, 2022), while fair treatment across outcomes, processes, and interpersonal interactions signals respect and dignity (Colquitt et al., 2019). When such conditions are perceived, employees internalize them as organizational support, resulting in stronger emotional bonds and commitment.

Building on this perspective, multiple studies affirm that POS is a key mechanism through which CD and OJ translate into engagement. Jia-jun & Hua- ming (2022) found that career growth, when supported by POS, strengthens affective commitment and engagement. Similarly, Aggarwal et al. (2022) and Chen et al. (2024) demonstrated that distributive and procedural justice significantly predict POS, fostering trust and emotional security. Imran et al. (2020) further highlighted that POS enhances sustainable engagement through psychological states like thriving and flourishing. These findings establish POS

as a central mediating mechanism in translating developmental and fairness- based practices into long-term engagement.

H3: Career Development has a significant positive effect on Perceived Organizational Support.

H4: Organizational Justice has a significant positive effect on Perceived Organizational Support.

H5: Perceived Organizational Support has a significant positive effect on Sustainable Engagement.

H6: Perceived Organizational Support mediates the relationship between Career Development and Sustainable Engagement.

H7: Perceived Organizational Support mediates the relationship between Organizational Justice and Sustainable Engagement.

The following is the framework of this research:

Figure 1. Conceptual Framework

Indicator Reliability and Convergent Validity

To evaluate convergent validity, the outer loadings of each indicator were examined. Only items with loadings ≥ 0.70 were retained, while those below the threshold were further reviewed based on their conceptual relevance and empirical contribution. After considering AVE, cross-loading, and model fit indices, a total of 4 indicators were removed because they did not provide optimal contribution to construct reliability and validity. The final configuration demonstrated adequate convergent validity.

Composite Reliability (CR), Cronbach’s Alpha (α), and Average Variance Extracted (AVE) values for all constructs exceeded the minimum thresholds recommended by Hair et al. (2022), confirming high internal consistency and convergent validity.

Table 1. Construct Reliability and Validity

Table 2. Heterotrait-Monotrait (HTMT) Ratios

Table 3. Hypothesis Testing Results

The first hypothesis (H1), which states that career development has a significant positive effect on sustainable engagement, is confirmed. In the context of PT Enviromate Technology International, employees who perceive clear career trajectories, fair advancement systems, and meaningful professional development are more likely to maintain a deep emotional, cognitive, and behavioral commitment to their work. This finding aligns with the Social Exchange Theory (Blau, 1964), which posits that when organizations invest in employees’ growth, individuals reciprocate with heightened engagement. Prior studies by Ahmed et al. (2020) and Jena & Nayak (2023) similarly highlight that structured and empowering career development enhances engagement by strengthening future orientation and psychological ownership at work.

From a practical standpoint, second-order analysis identifies career provision as the most influential dimension in shaping engagement, followed by self-improvement and work quality enhancement. These findings suggest that employees are especially motivated by transparent access to career paths, constructive performance feedback, and personalized learning opportunities. Organizations are encouraged to communicate promotion criteria clearly, provide development roadmaps, and embed feedback mechanisms that acknowledge both outcomes and effort. Doing so helps foster a climate of trust and optimism, enabling sustainable engagement among employees in high- pressure EPC environments.

The second hypothesis (H2), which proposes a direct positive relationship between organizational justice and sustainable engagement, is not supported by the findings. Although fairness is a fundamental element of a healthy organizational climate, in this study it does not directly predict sustained employee engagement. This is particularly relevant in the EPC sector, where structural justice alone may not be emotionally compelling enough to generate long-term commitment. As supported by Piotrowski et al. (2021) and Rahman & Karim (2022), procedural and distributive fairness may lay the groundwork for trust, but they require complementary support systems to translate into engagement.

Nevertheless, the managerial implications are vital. Procedural justice was identified as the most impactful dimension, followed closely by informational justice. These results underscore the importance of transparent decision-making processes, inclusive policy design, and respectful communication between leaders and team members. To create a culture where fairness is felt rather than merely observed, managers should foster participative forums, open channels for feedback, and consistent interpersonal treatment.

When fairness is perceived as genuine and human-centered, it enhances psychological safety, which is foundational for enabling other drivers of sustainable engagement.

Hypotheses H3, H4, and H5 are all supported, demonstrating that perceived organizational support (POS) positively influences sustainable engagement and is shaped by both career development and organizational justice. Furthermore, hypotheses H6 and H7 are also confirmed, revealing that POS significantly mediates the relationships between career development and engagement, as well as between organizational justice and engagement. These findings confirm that sustainable engagement is not merely a result of structural or procedural inputs but is deeply rooted in employees’ perceptions that the organization genuinely values and supports them.

This mediating role of POS reflects its dual nature as both an interpretive and emotional mechanism—a lens through which employees assess organizational intentions and a channel through which they experience relational trust. Among its dimensions, supervisor support emerged as the dominant driver of POS, followed by rewards and job conditions, while fairness, although relatively less influential, remains a significant supporting dimension. This indicates that the interpersonal interface between leaders and employees is crucial in fostering a sense of organizational care. To strengthen POS, organizations should equip supervisors with empathetic communication skills, coaching capabilities, and relational leadership practices. Additionally, fair compensation systems and healthy work environments must be maintained and regularly reviewed. As highlighted by Suharto & Suprapto (2023), POS plays a strategic role in building resilience and psychological endurance, especially in project-intensive sectors like EPC, where engagement must be continuously renewed in the face of high demands and uncertainty.