Induced Treg (iTreg) cells are essential for tolerance and can be used therapeutically, yet their stability in vivo and mechanisms of suppression are unresolved. Here, we used a treatment model of colitis to examine the role of autologous IL-10 in iTreg cell function. Mice treated with IL-10+/+ iTreg cells in combination with IL-10/ natural Treg (nTreg) cells survived and gained weight, even though iTreg cells were numerically disadvantaged and comprised just ~20% of all Treg cells in treated mice. Notably, ~85% of the transferred iTreg cells lost Foxp3 expression (ex-iTreg) but retained a portion of the iTreg transcriptome which failed to limit their pathogenic potential. The TCR repertoires of iTreg and ex-iTreg cells exhibited almost no overlap, which indicates that the two populations are clonally unrelated and maintained by different selective pressures. These data demonstrate a potent and critical role for iTreg cell produced IL-10 that can supplant the IL-10 produced by nTreg cells and compensate for the inherent instability of the iTreg population.