Hastings, 73 -- a close ally of Speaker John Boehner, R-Ohio -- has represented the central Washington district since 1994, the Hill said.
The Hill, Roll Call and the Washington Post said the seat Hastings is leaving is expected to stay in Republican hands.
Hastings is the 18th member of Congress to announce retirement this term, Roll Call reported.
"Two decades ago, the people of central Washington first voted to place their trust in me to represent them in Congress," Hastings said in a statement. "In the nine subsequent elections, I've been humbled to have been given the privilege to serve as their common sense voice and to work for solutions to improve our local communities and pursue a better, brighter future for our nation.
"It is with deep appreciation for that privilege that I announce that this will be my final term in office and that I will not run for reelection in November," he said.
Washington state Republicans seen as possible successors include former NFL tight end Clint Didier; state Sens. Sharon Brown, Janea Holmquist Newbry and Curtis King; state Reps. Brad Klippert, Matt Manweller and David Taylor, Roll Call said.