"This morning Speaker Ryan shared with his colleagues that this will be his previous year as a member of the House", Ryan aide Brendan Buck said in a statement. He will serve out his full term, run through the tape, and then retire in January.
Ryan's future on Capitol Hill had been a topic of conversation ahead of a hard campaign season, as Republicans try to keep the House majority.
Ryan, who was elected speaker in 2015 to replace outgoing John Boehner, is among a wave of House Republicans who have retired or announced they will not seek re-election in this year's mid-term elections.
Peter Baker, chief White House correspondent for the New York Times, confirmed that Ryan would not be seeking re-election.
The party has seen a large number of retirements, and Ryan's exit is certain to sap morale as Republicans seek to contain a surge in enthusiasm from Democrats, whose fortunes have been buoyed by the unpopularity of President Donald Trump. "Obviously, there's a lot of speculation, but I've been real clear for a long time, I don't want to get into speculation", he told Fox News, adding, "We've got to make sure we keep the majority".
"He is not running for reelection", said Rep. Mark Meadows, R-N.C., chairman of the House Freedom Caucus.