Myhill joined Hull from Aston Villa in a £50,000 deal six years ago.
Related ArticlesHull sign Venegoor of HesselinkTurner eyes England placeBrown defends Turner saleThe player has re-established himself as the club's first-choice goalkeeper after losing his place to Matt Duke for a spell midway through last season.
Manager Phil Brown said: "Over the last two or three years, I have seen that Boaz Myhill is a Premier League goalkeeper, there is no doubt about that.
"He stepped up to the plate very admirably last season, albeit in difficult circumstances with Matt Duke breathing down his neck all year.
"I know Dukey got himself into the first team for six or seven games and that must have surprised Bo at the time, but he has come back stronger.
"I'm delighted to get Bo tied up to a decent contract long term."
Brown added there could be "one or two more announcements in the near future" regarding the contracts of other players.
News of Myhill's deal comes soon after the club completed the signing of former Celtic striker Jan Vennegoor of Hesselink.