Hamm confirmed the date of Sunday, March 25 for the show's return to AMC during a chat with the Doug Loves Movies podcast.
Mad Men is expected to air on Sky Atlantic in the UK shortly after its American premiere date.
Matthew Weiner's long-running negotiations with AMC over finances and episode lengths delayed the fifth season from its usual summer slot and extended the off-air hiatus between the fourth and fifth season to 17 months.
Very few details are known about the fifth run of the 1960s ad agency drama except that Hamm, who plays lead Don Draper, has directed the first episode.
Christina Hendricks (Joan Harris) recently assured fans that the upcoming series will be "worth the wait" and promised more "great storytelling" when the show returns.
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Watch a teaser for Mad Men season five below: