The England international's shot from the edge of the box deflected in off the arm of Latics defender Gary Caldwell, deceiving Ali Al-Habsi in the visitors' goal before resting in the back of the net.
But, despite the goal having been inadvertently diverted in by Caldwell, the 31-year-old believes the strike should go down in his name.
"It's mine," he told the club's official website. "I don't know about 'claiming it'; it is a shot that was going on target which has gone in the other side of the goal. As far as the rules go, it's my goal."
|9/1||Leon Osman is 9/1 to open the scoring against Chelsea with Paddy Power|
Osman continued: "It's a great sign of the character we have. We were picking up draws and we needed to find a way of turning them into wins and we have done that in the last couple of games.
"Wigan made it difficult for us and played some really good stuff at times but the hectic Christmas period is all about picking up as many three points as you can and we did that.
"Chelsea have been strong over the years and increased their firepower this year. It is going to be difficult but we are full of confidence and we make it a tough game for anyone to come to Goodison, so hopefully we will do that again."