England flop Carson smashed the ball against Nigel Reo-Coker and the ball flew straight back into the net after Jermain Defoe had earlier given Pompey the lead with a stupendous chip.
The win leaves Portsmouth still fighting for a UEFA Cup spot and they also have an FA Cup semi-final to look forward to next month.
Shaun Maloney was first to threaten for Villa in a lively opening as he fired in a 20-yard drive that David James got his body behind to save.
Sulley Muntari hit back for Portsmouth in the eighth minute when he fired a trademark 25-yard pile-driver that Wilfred Bouma did well to block for a corner.
Portsmouth took the lead in the 11th minute thanks to a beautiful goal by Defoe. The former Spurs striker latched onto Glen Johnson's long ball and delicately lifted the ball over Carson from 18 yards out on the right-hand edge of the penalty area.
Defoe has now hit six goals since his move from White Hart Lane in the January transfer window and looks like he is really enjoying himself on the south coast.
Milan Baros was next to threaten against his former club. He went on a mazy run before shooting from 20 yards but Carson dived to his right to make the save.
England goalkeeper James pulled off a wonderful block to deny dangerman John Carew. The giant forward nodded on Ashley Young's cross, but James reacted magnificently to claw the ball away.
On this form James looks every inch a top-class goalkeeper and he could still be between the posts for England in the 2010 World Cup in South Africa.
Portsmouth doubled their lead seven minutes before the break through Reo-Coker's comedy own goal. Carson rushed out to clear from Defoe but hit his pass straight against Reo-Coker and the ball rebounded off the midfielder and into the back of the net.
Carson was mercilessly ribbed by the crowd for the rest of the match and he looks woefully short of confidence compared to England rival James at the other end.
Another player short on confidence is Gabriel Agbonlahor and he missed the easiest chance of the game.
Gareth Barry got to the by-line and squared the ball to the young striker who somehow managed to miss with the goal at his mercy.
His goalless run now stretches to ten games and he will not get an easier chance to break that duck.