The 39-year-old has raced with the Trek-Segafredo outfit and the RadioShack team that preceded it since 2010, and before that spent six seasons with Euskaltel-Euskadi.
A loyal domestique, Irizar's wins were few in number, with a time trial victory at the 2010 Tour du Poitou Charentes and the overall win in the 2011 Ruta del Sol his only individual results. But the likable rider was part of numerous team successes, including Chris Horner's 2013 Vuelta a España overall win and Fabian Cancellara's Paris-Roubaix/Tour of Flanders doubles in 2010 and 2013.
Irizar is also a survivor of testicular cancer, and his bond with Lance Armstrong over their shared history was in part responsible for him being hired to the RadioShack team in 2010.
"When I was recovering from the cancer I had 2 goals and reasons to fight: 1. To become a daddy. 2. To turn pro and have a long career. Thanks to many of you, today I can say that I have achieved both them. Huge thanks to everyone that has made this possible," Irizar wrote on Twitter.