Cherries manager Iraola said: "I'm very happy to sign the contract. For me, it is a matter of renewing the confidence from both sides.
"We have had a good experience with our first season together in the Premier League, and I am happy that both sides want to continue the relationship further.
"I'm proud that we achieved the points record. We are playing in a difficult competition, with very good opposition.
"The season started slowly, but I think we improved a lot and are playing in the right way.
"We have to continue improving the team, because the level of the Premier League is really high, and I'm looking forward to working with (technical director) Simon (Francis) and the rest of the team over the summer to help us do that.
"I would like to thank the supporters for everything in our first year together.
"I am thankful that they were supporting us even in the beginning when we were not winning games, and that they have been very helpful to the players for the whole year."