Speaking to BBC's Nolan Show, the 53-year-old entertainer from Donegal said nerves had impacted his performances.
He said his anxiety was sometimes so bad he had struggled to walk down the stairs before the live show.
Mr O'Donnell became the third celebrity to leave the competition at the weekend after failing to wow the judges in the dance off.
He and Kristina Rihanoff faced sports presenter Kirsty Gallacher and Brendan Cole.
But mistakes saw him being sent home.
Mr O'Donnell and his partner performed the American Smooth to Frank Sinatra's Fly Me to the Moon, while Gallacher and Cole performed a Paso Doble to U2s Beautiful Day.
Speaking on Saturday night's show, judge Craig Revel Horwood said: "One couple did really, really well in the dance-off and one couple, I am afraid, made a lot of mistakes.
"I am going for the couple that was the most powerful, and that was Kirsty and Brendan."
Mr O'Donnell told the Nolan Show that his nerves took him by surprise.
"If I didn't have to do that live show every Saturday night it would have been the perfect experience.
"The strange thing is I hadn't anticipated being nervous, I thought it would be hard to learn the routines, but I never anticipated that kind of nerves.
"I can't explain it. It's ridiculous from the point of view of someone who has been on stage as many times as me."
He told the show he couldn't speak highly enough of the crew, dancers and judges on Strictly but said he was "relieved" to have been voted off.
"The dance off was a disaster". He said.
"I forgot everything and maybe I was quite happy to go to tell you the truth."
Mr O'Donnell said he wouldn't be doing any more reality TV, but he would keep dancing.

Stewart, 26, netted a hat-trick and Hemmings, 24, scored twice as Dundee beat Dumbarton 6-2 on Saturday.
The attacking pair were also regular scorers for the Dark Blues last season, Hemmings notching 25 goals, Stewart 11.
"They are fantastic players. Hopefully we can keep hold of them for a bit longer," O'Dea, 29, told BBC Scotland.
"They are obviously two good pals of mine and it is about getting the right move, it's not moving for the sake of it.
"If you go to England you will probably earn more money but the two of them can really progress and go on to a very high level in the game. It's important if they did move, it's the right move.
"To replace them, it's virtually impossible, because you don't have the money to go and replace them."
Former Rangers youth player Hemmings and Stewart played together at Cowdenbeath and have scored almost 60 goals between them for Paul Hartley's side in the last two seasons.
"You need to have recruitment, which Dundee do have, and you need to have an eye for a player, which our manager does have," added Republic of Ireland cap O'Dea, who headed Dundee's other goal against Dumbarton.
"These two lads came from lower league clubs. Credit to the manager, he's found talent in lower leagues, which there is an abundance of.
"But to actually go and replace them straightaway is virtually impossible."
Rangers, Aberdeen and Leeds United are among the clubs rumoured to be keen on prising Stewart away from Dens Park.
"There's going to be interest in Greg the way he's performed over the last two years," said manager Hartley after what he called a "sublime" performance from the attacking midfielder on Saturday.
"But we don't want to sell him. There's no way we could replace him - no danger about that."
Irish singer Daniel O'Donnell was "relieved" to be voted out of Strictly Come Dancing at the weekend.
[NEXT_CONCEPT]
Dundee defender Darren O'Dea believes team-mates Kane Hemmings and Greg Stewart would be "virtually impossible" to replace in the short term.