Materialism at work refers to a higher importance attached to extrinsic (e.g., money, fame, image) versus intrinsic (self-development, affiliation, community participation) employees’ ‘aspirations’. Research from self-determination theory has consistently found that materialism at work is strongly detrimental for both employees and organizations. For example, materialism is negatively associated with lower job satisfaction and engagement and positively associated with higher turnover intentions and job insecurity. Unfortunately, there are no viable strategies for reducing materialism in the workplace yet. In this sense, based on emergent research in psychology, we theorized that dispositional gratitude—a key construct within the Positive Organizational Psychology field—could be a protecting factor against materialism. Further, we conducted a three-wave longitudinal design among a large sample of Chilean workers (n = 1841) to test, for the first time, the longitudinal link between gratitude and materialism. We used two novel methodologies: A cross-lagged panel model (CLPM) to test between-person changes and a trait-state-occasion model (TSO) to test within-person changes. We found that both the CLPM as well as the TSO models showed that gratitude at work prospectively predicted further lower workplace materialism. Specifically, the CLPM shows that individuals with higher than average gratitude at Ti, are more likely to show lower than average materialism at Ti+1. The TSO shows that individuals with a higher than their usual level of gratitude at Ti are more likely to show a lower than their usual level of materialism at Ti+1. Important implications for materialism research as well as for the Positive Organizational Psychology field are discussed.