Keys said in a statement he was "deeply sorry" for comments he made regarding lineswoman Sian Massey before Saturday's Premier League match between Wolverhampton Wanderers and Liverpool.
Keys was initially suspended from broadcasting on Sky while his co-presenter and chief analyst Andy Gray was sacked following the emergence of a number of other recordings in which the former Scotland international made sexist comments.
"It was wrong and should not have happened," said Keys, who worked for Sky Sports for 20 years and has fronted their Premier League coverage since it's inception in 1992.
"I have thought long and hard and reached the decision that it is time to move on.
"Going forward without Andy would have been almost impossible.
DISAPPOINTING END
"It is disappointing that Richard's career at Sky should end in these circumstances," Barney Francis, managing director of Sky Sports, said in a statement.
"However, Richard recognises that his comments at the weekend were unacceptable and we note that he has made a full and public apology."
Former Scotland international Gray, meanwhile, who was fired on Tuesday, issued a statement through his lawyers saying: "I am very sorry that certain comments made by me have caused offence.
"Such comments were made off air to work colleagues and, of course, were never intended to be broadcast.
"I was very upset when the comments were brought to my attention. It was my intention to apologise on Monday night when I was back on air for the Bolton v Chelsea game.
"Sadly I was unable to do so as I was suspended by Sky Sports and have now been sacked.
"Football is my life and I am devastated by losing the job that I love. I am equally upset that third parties have been dragged into this issue and I ask that the media respect their privacy so that they can continue in their roles."
Host Keys and pundit Gray were initially suspended by the broadcaster after they were recorded questioning whether Massey "knew the offside rule".
Speaking before kick-off Keys had said: "Somebody better get down there and explain offside to her". Gray retorted: "I know, can you believe that? A female linesman...".
Keys later added: "The game's gone mad" before going on to mock recent comments about sexism in football made by West Ham United vice-chairman Karren Brady, one of the highest-profile women in the game.
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