People often adjust their behaviours and preferences to align with others, a phenomenon termed social influence or social contagion. Social influence can have a profound effect on our economic preferences, with important implications for financial decision-making and making rational choices. Here, we review recent findings in neuroeconomics, elucidating the psychological, computational and neural mechanisms that underpin social influence during value-based decision-making. We examine how others’ decisions can shift our own economic preferences, regarding risk-taking, temporal discounting, effort discounting and moral preferences. Additionally, we discuss the lifespan similarities and differences in susceptibility to social influence. Finally, we cover studies revealing the neural basis of susceptibility to social influence and highlight key common brain areas across studies that could underpin these effects. We end by considering the implications of strong evidence of susceptibility to social influence on economic preferences, the challenges and opportunities of this influence and how future studies could harness it to create positive changes across the lifespan.