'The Chairman and the Board of Directors would like to place on record their thanks for the dedication and commitment Roberto has shown during his three seasons with the club.
'Roberto has been a great ambassador for the club, conducting himself, at all times, with the utmost integrity and dignity.
'He secured the club its highest ever Premier League points total, a place in the last 16 of the Europa League and appearances in both domestic cup semi-finals. He has also played a key role in the development of several young players, managing their progression to the Everton First Team and International honours.'
The club also cancelled the planned end of season awards following Martinez's sacking and a statement on the Everton website read: 'Following the departure of Roberto Martinez, the Club's End of Season Awards, due to be held at St George's Hall tonight, has been postponed.
'Roberto has shown great commitment and dignity throughout his time at Everton and the Club feels it should reciprocate by rescheduling the event. The Club hopes that those due to attend would agree that the planned celebration would be inappropriate in the circumstances.
'We appreciate that many people will be disappointed but we hope there will also be an understanding of why this decision was taken.
'The Club will invite all who had planned to attend to an event before the start of next season at which players and Club officials will also be in attendance.
'The Club will contact all guests as soon as possible and will provide rearranged details as soon as they become known.'
Frank de Boer is the early favourite to succeed him after leaving Ajax while his fellow Dutchman Ronald Koeman, in charge of Southampton, is also fancied.
De Boer's brother Ronald has backed his sibling to for the vacant position at Everton and told Sky Sports News HQ: 'Frank is interested in the Everton job, but it's not up to him to make the move, that's up to the club. In my eyes he's the right man for that job,' Ronald said.
'He thought he was going to fulfil his ambition of managing in the Premier League but talks with Tottenham collapsed at the last minute.
'When you see what Ronald Koeman has done at Southampton I would argue that Frank is at least as good as him when you see what he has achieved at Ajax.
'I think Everton would be a good fit for Frank. It's the sort of club where he'd be given the chance to show his qualities and do something special. He made up his mind to leave Ajax two months ago because he needed a change.'
David Unsworth, the Everton Under 21s manager, will take charge of the side against Norwich.
The weight of public feeling towards Martinez was something new major investor Farhad Moshiri could no longer ignore and the decision has been taken following Wednesday's 3-0 capitulation at Sunderland.
Everton's players were on a scheduled day off on Thursday but Martinez, who usually arrives in for work every day at 8am, did not come into Finch Farm, the club's training base, as normal.
Following the no-show, the players concluded they had lost their manager.
Their end-of-season awards will be staged at St George's Hall in Liverpool city centre on Thursday evening and fans were expected to congregate on St George's Plateau to protest about Martinez's performance.
This is not a decision that Everton's board will have wanted to take - they have only sacked one manager since the turn of the century - but results, particularly since the turn of the year, have been impossible to ignore.
Following defeat at the hands of the Premier League's 17th-placed side Martinez remained defiant about his future - and claimed the FA Cup semi-final defeat by Manchester United had hit them hard.
Asked if he believed he retained his players' support, the former Wigan boss said: '100 per cent - I know the players gave everything they have.'
'Since the FA Cup semi-final it has been difficult for us to get that belief and intensity in the league and Sunderland were the opposite - a fully focused team who created a good momentum because they were close to finishing the job.
'We were a little bit pedestrian but I thought the effort and intent was there in a very competitive game.
'It was a very tough result for us to take. We kept pushing and creating chances and in the latter stages of the game we hit the post and the bar and we didn't get anything.
'Overall we fought for every ball and we put in a lot of effort, but Sunderland scored the goals.'
The pressure on Martinez appeared to have been alleviated when Romelu Lukaku scored twice in a thrilling FA Cup quarter-final victory over Chelsea at Goodison in March.
But the Toffees' already patchy Premier League form collapsed entirely following that win against Guus Hiddink's men.
Martinez has presided over a miserable run of one win in 10 league outings, while Everton's cup ambitions were derailed by Anthony Martial's last-gasp winning goal at Wembley.
Supporter dissent grew after the Blues' supine display last month in losing 4-0 to Merseyside rivals Liverpool - the second time in Martinez's three-year reign that Everton have been on the end of that particular scoreline at Anfield.
Even before that humiliation across Stanley Park fans had become disenchanted with the boss who led them to a fifth-placed finish in his first season in charge, following his appointment to succeed David Moyes in 2013.
Everton slipped to 11th in Martinez's second term.
This campaign has been blighted by a succession of defensive calamities, which have seen the Merseysiders surrender a succession of winning positions.
Bournemouth, Norwich, Stoke, Chelsea and West Ham are among the teams to have taken points from the Toffees, after falling behind to Martinez's team.
But a team widely billed as Goodison Park's finest since the club's heady mid-1980s trophy-winning days has lost its spark entirely in recent weeks.
They were convincingly beaten by new champions Leicester City four days before defeat at the Stadium of Light and Martinez gave little evidence that he is the man to arrest the slump.
