Dunn has missed the last three games with a facial injury but will come back after replacement Steve Collis hurt his thigh during the 2-2 draw at Stockport on Monday.
Manager Gary Johnson said: "Chris is available for selection. He wants to play and he has more than proved to me that he is both physically and mentally ready for the game.
"He will probably have to wear some sort of protective mask or helmet but the injury is well healed and he's ready to play."
On-loan Doncaster defender Byron Webster picked up a hamstring injury against Rotherham on Good Friday and will miss the rest of the run in as the Cobblers look to stay in the Football League.
Striker Leon McKenzie will also miss the rest of the season after he picked up a thigh injury at Stockport but fellow forward Billy McKay is now fit after a dislocated elbow.
A first win in 19 games could be enough to secure their place in League Two if Barnet lose at Accrington.
Source: PA
Source: PA