Wales are favourites to progress from this Battle of Britain in Paris, largely down to the supreme capabilities of Bale, with the Real Madrid star having scored three goals in as many games on the way to securing top spot in Group B.
O'Neill twice pitted his wits against Ronaldo during qualification for the 2014 World Cup, leaving Bale's club team-mate goalless on his 100th cap - a 1-1 draw in Porto - before being on the receiving end of a hat-trick in a 4-2 loss.
And the 46-year-old believes his side have what it takes to stop Bale on Saturday.
"Gareth Bale's a huge player for Wales, he's shown that in the tournament already and he's shown that in qualification," O'Neill told a pre-match news conference at the Parc des Princes.
"I've had that task as a manager before, trying to deal with Cristiano Ronaldo, so I know how to deal with that for large parts of the game.
"We had that in the first game against Poland with Robert Lewandowski as well.
"Once you get to this stage of the tournament you're always going to have to deal with special players.
"We'll be ready to deal with Gareth Bale. We know his threat, his threat at set-pieces. We know his running power, his pace and his goal threat but we're ready to deal with that.
"I think in previous games and qualification games the players have dealt with top, top players.
"We need Gareth Bale to have a quiet night and it's up to us to make sure that's the case."
O'Neill takes confidence from Northern Ireland's exploits at this venue three days ago when world champions Germany were restricted to a 1-0 win.
"We've been incredibly strong defensively. On Tuesday night we played a team full of world-class players," he said.
"We had a performance that was fantastic. Yes, we relied on our goalkeeper to make some good saves but I don't think you're going to play the world champions and not have>