The striker, on loan from MK Dons, will team up with former Dons defender Mathias Kouo-Doumbe, and fellow striker Clive Platt.
"The over-riding factor is to come and play some games and help the team out any way I can," the 29-year-old told the club's official website.
"I've known (Clive) Platt for a number of years now and still keep in contact with him.
"It is nice to come and have a few familiar faces here.
"I was at the Dons with Matty Doumbe as well so I know him, so it is always good to have a familiar face when you come to a new club".
The 29-year-old will be at Northampton until January 4, after completing the move on loan deadline-day.
McLeod, who has played for 11 clubs throughout his career, could feature against Accrington in Saturday's Sky Bet League Two clash at Sixfields.