It was a special day for the left-arm spinner who claimed three for 54 from 30.4 overs as the home side were restricted to 264 for eight at the close, having won the toss and elected to bat.
Tom Taylor also enjoyed success with the ball, taking three for 72, as Lancashire collapsed from a very healthy position of 143 for two.
Preston-born Kerrigan won the County Championship with Lancashire in 2011, but was released by the club in 2018 after struggling for form and game time.
Still only 31, Kerrigan has been given the chance to resurrect his career by Northants after a spell without a club, and he admitted he enjoyed the first day of his return to the place where it all began for him.
"It was really enjoyable," said Kerrigan, who has one Test cap for England.
"There was definitely a point over the last few years where I thought I would not be back here bowling in a competitive game, so I'm pretty proud to be out here today and it was good to get some overs.
"I was pretty nervous at the start but was able to get into it and hit my areas and thankfully I then stuck in there most of the day."
Kerrigan was one of three changes made by Northants from their opening draw with Kent, with Saif Zaib and anther ex-Lancashire man in Luke Procter also getting the call.
The three who missed out were the injured Charlie Thurston, Alex Wakely for personal reasons, and Gareth Berg.
Ripley had spoken in the week about wanting to get Kerrigan in to give skipper Adam Rossington more options and variety, but the spinner admitted he faced a bit of an anxious time before getting the nod.
"There were a lot of questions being asked of Luke Procter and I this morning about the pitch," said Kerrigan.
"We were panicking because it looked a bit different to the usual day one pitches here, as usually you get a bit of moisture in the track and it tends to not be the worst time to bowl.
"It's a good pitch and there's a little bit of spin there and something for the seamers with a few little cracks which the ball will do a bit off.
"There's something in it for everyone but we saw today that there were flat periods when it was tough to get people out."
Best performers with the bat for the home side were Alex Davies and Josh Bohannon, who both hit half-centuries, but nobody else got more than 26 as the Northants bowlers showed excellent control.
As well as Kerrigan's miserly stint, seamer Ben Sanderson's 23 overs only cost 44 runs.
LV= Insurance County Championship Group 3
Day one close: Lancashire 264-8 (100 overs, Bohannon 68, Davies 57, Kerrigan 3-53, Taylor 3-72, Sanderson 1-44)