Finding a fitting endorser has proven to be one of the most delicate and critical tasks of influencer marketing. This research explores the relevance of the congruency of the influencer personality with (1) brand personality and consumers' (2) actual/(3) ideal selves. Additionally, the (4) moderating role of involvement is considered, the impacts on post attitude/belief, brand trust and purchase intention are thereby studied. The novelty of this study lies in the integral examination of the types of congruencies and involvement in the context of influencer marketing as well as the consideration of their impact on the brand-related variables. Based on an online survey with 547 participants analyzed by means of structural equation modeling in SmartPLS, partly counterintuitive findings were produced. When the involvement level rises, congruence with consumers' actual selves becomes more important. Under low-involvement conditions, practitioners should pay more attention to influencers' fit with consumers' ideal selves. An adequate fit between brand and endorser is paramount and becomes even more important under high-involvement conditions. Overall, this study reveals that the three types of congruency and involvement interact in a very unique way in the context of influencer marketing. © 2021 The Authors. Journal of Consumer Behaviour published by John Wiley & Sons Ltd.