One of the best pitchers in baseball is heading out West.

The Mariners are signing reigning AL Cy Young winner Robbie Ray to a five-year, $115 million contract, The Posts Joel Sherman confirmed.

Ray, 30, has a full no-trade clause over the first two years of the deal and an opt-out after the third year.

The left-hander led the AL in ERA (2.84), innings pitched (193.1), strikeouts (248), ERA+ (154) and WHIP (1.045) this past season for the Blue Jays. ERA+ normalizes ERA to include external factors such as ballparks and opponents — 100 is league average, so 154 means 54 percent greater than league average. WHIP is walks and hits per inning pitched.

Ray’s $115 million deal narrowly edges out the contract that his now-former team, the Blue Jays, gave Kevin Gausman over the weekend — Toronto is paying Gausman, the former San Francisco Giant, $110 million for five years.

The Ray news also comes after the Mets backed up the Brinks truck to give Max Scherzer a three-year, $130 million deal.