The Covid-19 pandemic has heightened public interest and awareness of the importance of living sustainably while sparked interest in businesses that make "good" use of their green marketing campaign. Indeed, green marketing has gained wide acceptance within the business world as a viable competitive strategy to grab and win customers' attention in the marketplace. This research sought to investigate how the green advertising environmental claims affect consumers' trust in the green advertisement. The mediating role of involvement was examined. Data from 185 respondents in Malaysia were collected and analysed using SPSS. Adapted scales were used to measure environmental claims, environmental involvement, and trust and their relationships were tested using PROCESS macro and SPSS. The findings revealed that environmental claims had a significant direct and indirect effect on consumers' trust via environmental involvement. Environmental involvement partially mediated the relationship between environmental claims and consumers' trust toward the green advertisement. Results indicate that environmental claims did enhance consumers' trust in green advertisements. Moreover, consumers with deep environmental concerns had higher trust in the green advertisement if the advertising (environmental) claims included relevant facts and were executed correctly. The results of this study can be used as a reference for future research of consumers' attitudes toward green marketing/advertising and the types of advertising execution in green marketing. Furthermore, the findings of this study also add to the growing body of knowledge about green marketing in developing countries like Malaysia, which has a large potential market for green products. This study is limited to only two constructs, many variables such as advertising's execution techniques and media strategies can be included for future research directions.