Danny Baker has expressed his deep regret at the Twitter storm that led to his sacking on Thursday, describing it as "one of the worst days of my life".
The former BBC Radio 5 Live presenter was sacked over his chimp tweet about the Duke and Duchess of Sussex's baby.
The 61-year-old tweeted on Friday that "it was a genuine, naive and catastrophic mistake".
He admitted he was "foolish" to later try to make light of it.
The tweet, which was removed, showed an image of a couple holding hands with a chimpanzee dressed in clothes with the caption: "Royal Baby leaves hospital".
Baker denies that there was racist intent behind the post but admits he is now "paying the price... and rightly so".
Good morning, everyone.— Danny Baker (@prodnose) May 10, 2019
Following one of the worst days of my life I just want to formally apologise for the outrage I caused and explain how I got myself into this mess.
I chose the wrong photo to illustrate a joke. Disastrously so.
He wrote: "Following one of the worst days of my life I just want to formally apologise for the outrage I caused and explain how I got myself into this mess.
"I chose the wrong photo to illustrate a joke. Disastrously so.
"In attempting to lampoon privilege and the news cycle I went to a file of goofy pictures and saw the chimp dressed as a Lord and thought, 'That's the one!' Had I kept searching I might have chosen General Tom Thumb or even a a baby in a crown. But I didn't. God knows I wish had.
"Minutes later I was alerted by followers that this royal baby was of course mixed race and waves of panic and revulsion washed over me... What had I done?
"I needed no lessons on the centuries slurs equating simians and people of colour. Racism at it's basest.
'Crass and regrettable blunder'
"But it was a genuine, naive and catastrophic mistake. There is of course little media/twitter traction in such a straight-forward explanation. The picture in context as presented was obviously shamefully racist. It was never intended so - seriously who on earth would 'go there'?"
He added: "Anyway I am now paying the price for this crass and regrettable blunder and rightly so. Probably even this final word from me will extend the mania. ('Dog whistle' anyone?) I would like to thank friends on here for their kinder words and once again - I am so, so sorry."
On Thursday, Baker joked with journalists on his doorstep that the tweet was a "stupid gag".
Broadcaster Scarlette Douglas, who works on 5 Live podcast The Sista Collective and The One Show, told the BBC: "I think somebody told him, 'What you've tweeted was incorrect, so you should maybe say something or take it down.'
"Yes, OK, he took it down, but his apology for me wasn't really an apology. I don't think it's right and I think subsequently what's happened is correct."
After reflecting on his comments the day before, Baker added: "I would like once and for all to apologise to every single person who, quite naturally, took the awful connection at face value.
"I understand that and all of the clamour and opprobrium I have faced since. I am not feeling sorry for myself. I [messed] up. Badly.
"I am aware black people do not need a white man to tell them this. Deleting it immediately and apologising for the awful gaffe I even foolishly tried to make light of it. (My situation that is, not the racism involved.) Too late and here I am."
However, Dr Pragya Agarwal, a psychology academic and equality campaigner, told the BBC that Baker's latest apology, while lengthy and detailed, "still feigns ignorance about the racist tropes, while continuing to play the victim".
"I am really struggling to see how Danny Baker could not have realised what he was posting. The history of racial slurs and monkey chants in football are well-known and so he must be aware of the connotations," she said.
Dr Agarwal said Baker's tweet was "particularly harmful because it came from someone who has a media profile".
"People admire and follow him, so it gives a signal to others that it is perfectly acceptable," she added.
"As a result, it has reminded black people and those of mixed-heritage that they are still 'othered'.
"It is important that we give people an opportunity to address and acknowledge their implicit biases in a safe and non-judgemental space.
"When we do this, we can begin to address the inequalities. If only Danny Baker had done so," she added.