The England international missed a golden chance against Stoke in Villa's last home game when his side were leading 2-0 - and it proved costly as Tony Pulis' side hit back to earn a 2-2 draw.
But O'Neill has complete faith in Agbonlahor who often had to operate as a lone striker until the signing of Emile Heskey in January and the return to fitness of John Carew.
O'Neill said: "Gabby has been a bit unlucky on one or two occasions. He probably should have scored against Chelsea, when Petr Cech made a save at the right-hand post, and he had a good chance against Stoke towards the end.
"Overall I'm not displeased with him. I think he's done great this season. Like most strikers, of course he thrives on goals and, the more you have, the more confidence you have about things.
"When he played on his own up front for three months he put an unbelievable amount of energy and determination into that and I thought he improved as a player because of it.
"The irony is now he's getting a bit more help with another centre-forward beside him, maybe one or two of the chances he feels he should have put away have gone begging.
"But he'll rectify that and I'm not talking about taking Gabby out of the firing line."
O'Neill, whose side face Tottenham in the Premier League on Sunday, is also delighted to have Carew back challenging for a starting place after a near three-month lay-off with his back problem.
The Norwegian was Villa's top scorer with 13 goals last season and his superb strike against Stoke took him into double figures for this campaign despite his long absence.
O'Neill said: "John is a bit away from proper full fitness but he's getting there after been out for about three months.
"That goal against Stoke will have been a major boost of confidence for him.
"The more players at this stage of the season that we have to choose from, which has been a bit of a problem for us for a while, the better chance we stand."
Villa have gone six games without a win in all competitions and are now level om points with Arsenal in the race for a Champions League spot.
O'Neill is focused on making sure Villa at least secure an automatic UEFA Cup place for next season before training his sights on higher goals.
He said: "We have still got 10 games to go and we can bounce back. There will be a lot of twists and turns, a lot of them, before the end of the season.
"With Manchester United winning the League Cup, then sixth place qualifies you for Europe. With the way we are going, if we pick up some more points in the next week or two, then we can secure that for a start.
"If we achieve that, then we can try and push on from there. Those are our goals at this minute.
"We have a number of games to try to win, we are going to try to stick with it. Am I still confident about finishing in the top four? We will still be there or thereabouts at the end."