It means the 24-year-old Republic of Ireland international has extended his stay at Goodison Park until the summer of 2018.
"I'm over the moon. I'm glad to get it all done and to sign for so long at a club like Everton is a great achievement - I want to be here for as long as possible," he told the club's website.
"Signing a contract here is fantastic and I'm really looking forward to the next couple of years.
"I'm going to keep working as hard as I have done since day one and keep improving every day in training to impress the manager.
"I'm really happy to have signed for the length of time that I have."
Coleman has missed the last three games through injury but has proved to be an increasingly useful addition on the right-hand side.
Having joined from Sligo Rovers in January 2009 for just £60,000 he made his debut against Benfica in October that year and later went on loan to Blackpool in their promotion-winning year.
He was rewarded with a new three-year contract in May 2010 and signed an improved four-and-a-half-year deal in January 2011 in a season in which he made 24 Premier League starts, his best to date.
Manager David Moyes found a place for him on the right of midfield for many of those early first-team appearances but has since slotted him back into the side on the right of defence.
Meanwhile, midfielder Darron Gibson has been sidelined for a month due to a thigh strain. On Monday afternoon Moyes was able to put a more specific timescale on Gibson's absence.
"I think he's going to be out for about four weeks," said the Scot.
The 25-year-old spent more than two months on the sidelines earlier in the season with a similar problem.
He missed 10 Premier League matches as a result and a further absence is a significant blow to Everton as he has been one of their key players since arriving in January.
Another injury is the last thing Moyes needed as he still has Kevin Mirallas (hamstring), Tony Hibbert (calf) and Seamus Coleman out, while Phil Neville (knee) had to be rested yesterday having played two matches in five days on his comeback from surgery.