A 1-1 draw with Wales on Thursday equalled the nine-match undefeated run set by Billy Bingham's side in 1986, before the milestone was beaten with a slender win over Slovenia on home soil.
O'Neill was elated after overseeing another positive result and tried to ensure the players understood the magnitude of what they had achieved.
"It's lovely to achieve something like that. It's for the squad – to go unbeaten for 10 games is a great achievement. I've emphasised that to the players," he said.
Conor Washington's first-half goal – his maiden strike for Northern Ireland in just his second cap – was enough to secure the victory.
O'Neill admitted the QPR forward's performances have boosted his chances of making the squad for the competition in France which starts in June, though nothing is decided yet.
"He's a raw striker. He's come on the international stage and showed what he can do. He made a goal out of nothing and it's a great night for him," the Northern Ireland coach continued.
"He's strong enough to fight against centre-backs and is particularly good in those inside channels.
"It would be unfair to say if he's on the flight to France. He's done himself no harm at all, not only in the performance, but how he's fitted in with the group. It looks like he's going to be an asset to us."
Roy Carroll denied substitute Milivoje Novakovic from the penalty spot in the second half in Belfast after Jonny Evans fouled Miral Samardzic in the area.
The 38-year-old claimed his pre-match research paid off and hopes it will help enhance his chances of permanently dislodging Michael McGovern in goal.
"I've been watching their penalties the last two days. I guessed the right way. He went that way in the videos," Carrol told BBC Two Northern Ireland.
"I enjoy playing for Northern Ireland. It's nice to keep a clean sheet as well. I want to be pushing for that number one shirt - nobody wants to be sat on the bench in France.
"I've had some bad nights out there at Windsor Park but tonight was fantastic."