How do we avoid unwanted influence when making a choice, and how do we know when our choices are free from such influences? Research shows that human decision processes are often biased by extraneous information and by previous habits. In the present study, we investigated whether free choices are biased in the same ways, and whether the subjective feeling of choosing freely can accurately track these sources of bias. Across three studies, we presented participants with a visual target cueing one of two directions. Participants were instructed to respond by adhering to the suggested direction, to oppose it, or to ignore it and make a ‘free’ choice. We varied the frequency of occurrence of each instruction (experiment 1), of each motor response (experiment 2), and of each visual cue (experiment 3). We found that previously learned stimulus-response mapping affected the ability to make free choices, as participants tended to follow the trained mapping. Moreover, in the detachment condition, participants consistently reported stronger subjective sense of freedom when their actions opposed the cue, rather than followed it. Strikingly, when participants learned through experience to oppose a cue, subsequent free choices evoked by that cue were associated with a boost in subjective freedom, irrespective of whether the response followed or opposed the cue. Thus, the increased subjective sense of freedom associated with opposition appeared to stick to the stimulus that had been repeatedly opposed. Taken together, these findings demonstrate the strong relationship between oppositional responding and subjective experience of freedom, showing for the first time that an illusory sense of autonomy can be acquired through trained opposition.