The 27-year-old, who played in seven Tests and 27 ODIs for England, retired last April after being diagnosed with a serious heart condition.
In a statement, Northants said that Taylor would work "on a consultancy basis" for the Royal London One Day Cup competition.
"I'm excited – They are a skilful side who have clearly done well in one-day cricket in the past," Taylor said. "I spent a bit of time commentating at the County Ground last season and am keen to offer up my expertise to the squad.
"Whilst my focus will no doubt be on the batsmen, I will be on hand to assist across all areas. I can't wait to get started."
Head coach David Ripley added: "James has a fantastic 50-over record, averaging over 50 which is obviously outstanding. It's very unfortunate for James not to be playing anymore, but it's great to see his desire to still be involved with the game. I believe he can offer good advice, and relay his one day cricket experiences on to our batsmen."
Meanwhile, former Northants captain David Sales has also joined the club as a part-time batting coach.