According to Nerd Reactor, a source has revealed that ABC has decided to renew Marvel's Agent Carter for a third season. Marvel hasn’t made the official announcement yet, but it has revealed that Marvel’s Agents of S.H.I.E.L.D. has been renewed for a fourth season.
Marvel's Agent Carter aired it's season finale last Tuesday. Fans of the series have been worried that ABC may cancel the series due to low ratings. However, the series has proven incredibly popular commercially and critically. Moreover, Atwell's Peggy Carter has appeared in several Marvel films, so its only fair that we get to see her story continue.
The word is not official yet, but hopefully we will be seeing Peggy's adventures continue for another season.