And 24-year-old Ifil tasted Premier League action with Tottenham ahead of spells with Colchester and Dagenham & Redbridge, who released him in May.
Kettering are also expected to sign goalkeeper Laurie Walker and defender Nathan Koo-Booth.
"David scored a lot of goals from midfield while he was here and we think that's really important," manager Morell Maison told BBC Radio Northampton.
"To have him in the side is a real coup for us. It didn't take a lot of arm-twisting - he's seen the project here and knows the football club.
"I laid out my vision for Kettering and how the team will play, and he buys into that.
"The chairman (Imraan Ladak) has backed the programme. Obviously I've had to justify what I'm doing but he's a football fan and he's supported me all the way.
"We've got some wonderful players here now."
Source: BBC Sport
Source: BBC Sport