The left-back, who has agreed a new four-year deal, had been the subject of two bids from David Moyes, who wanted to be reunited with his former player at Manchester United.
The 29-year-old has been persuaded to commit his best years to Everton, though, with the news offering a timely boost to the club ahead of the 22nd Merseyside derby. Everton are due to cross the city tonight to face Liverpool.
Victory would allow the Goodison side to leapfrog their city rivals in the Barclays Premier League table and bolster the club's ambition of qualifying for European competition. It is an aspiration which is shared by Baines and one which he evidentally believes he can fulfil at Everton.
Such confidence would only delight his manager further. "It is an important moment for us," said Martinez. "You are talking about January signings and bringing players into the club but no-one will be bigger than having Leighton Baines focused on being as good as he can be for Everton in the best years of his career.
"There were going to be a lot of clubs fighting for those years [of Baine's career]. He has been performing as one the best left-backs in European football and the best is yet to come because now he is in a position where he can enjoy the experience."
Few Everton supporters have been able to savour their trips to Anfield of late, with their side still to win their this century. Tonight could offer their best chance to address that run of form, with Liverpool missing defenders Daniel Agger, Mamadou Sakho, Glen Johnson, Jose Enrique and midfielder Lucas Leiva.
"There is still going to be quality players and the football ideas of both teams will come out but it is unfortunate a number of players are out of the game," said Brendan Rodgers, the Liverpool manager. "A lot of them are starting players and it would have made it a different game. It is unfortunate both teams are coming into the game with not the strongest squads, having picked up injuries."