James Milner and Gabriel Agbonlahor scored the goals for Villa, who moved into an impressive third place in the table.
O’Neill told Sky Sports: “It could have been more comfortable. We had a number of great chances to put the game beyond their reach, before we eventually did so.
“Those were worrying moments when you don’t take the chances. We created a lot of chances today, especially considering we were away from home.
“But we have been playing strongly. There is good drive and determination among the team and I was absolutely delighted when we scored the late second goal.
“I was expecting a really difficult game. A lot of Blackburn Rovers’ attacks started but then maybe failed about 15 to 20 yards from goal.”
He added: “What the record tells me is an awful a lot about the team. I think the performances of the team have been fantastic. A lot of the players are playing very, very well at the moment.
“There is a lot of determination and energy. I am delighted with 51 points on the board, which is fantastic for us. We have got to try and keep the momentum going, which is going to be really difficult.
“I believe they have belief now. They are developing into a reasonable team, not just with commitment and desire, which are essential, but with great ability. And today we showed that.”