The centre-back has committed the best years of his career to the Toffees.
Keane, who has played for England on several occasions, is now 27 and is happy with his place with the Merseyside club.
He also loves learning from an experienced coach such as Carlo Ancelotti.
"I have loved my three years at Everton and am looking forward to seeing what the future holds," Keane told the club's website.
"I am learning every day on the training pitch with the manager and all his staff. The manager is one of the best there has been.
"I am not happy just staying where I am at the minute. I want to keep improving and keep learning. My best years are definitely ahead of me.
"It's time we started producing results on the pitch. We want to finish higher in the table than we did last year and get into Europe."