The 32-year-old, who joined the club from Espanyol in 2007, reached 200 games for the Basque outfit in their 1-1 draw with Valencia last weekend.
"The game was like any other. There were still the same points at stake. I have been incredibly privileged in my career – very lucky. I've had a lot of fortune," he told reporters at a press conference.
"It's nice to be a part of history at this club – but the truth is every player is a part of this club's history."
Iraizoz started his youth career with Baskonia.