When social media influencers (SMIs) post sponsored content, it should be recognizable as such. However, there is no European Union-wide legislation governing sponsorship transparency, and monitoring practices differ significantly across member states. In Romania, where we conducted our study, such regulations are only just emerging, and there are weak monitoring policies regarding advertising disclosure on SMI branded posts. In this study, we examined how two different types of advertising disclosure commonly used on Instagram are likely to affect consumers’ behavioral outcomes, such as purchase intention and intention toward the SMI, mediated by the activation of conceptual persuasion knowledge (CPK), via negative affect and the trustworthiness of the SMI. We conducted a three-level between-subjects online experiment (N=248), manipulating the absence versus the presence of advertising, which came in one of two types, brand-unspecific (#ad, #sponsoredpost) and brand-specific (paid partnership with [brand]). Considering the mediation path via the trustworthiness of the SMI, findings suggest that the paid partnership disclosure had positive outcomes for purchase intention and intention toward the SMI.