New boss Lee Glover had spoken recently of his desire to keep Kennedy at Latimer Park but the efforts to do so have proved fruitless after it was confirmed that he has signed for newly-promoted Peterborough Sports.
Sports are gearing up for their first-ever season in the Vanarama National League North having won the Southern League Premier Central play-offs in the previous campaign.
And Kennedy was one of four new signings they announced over the weekend.
It serves as a blow for the Poppies with Glover facing almost a complete rebuild of the squad, which had already seen the likes of Connor Barrett, Alex Brown and Jordon Crawford depart.
Writing on Twitter, Kennedy said: “Thanks for all the memories @KTFCOfficial and all the best for the future.”
Also writing on Twitter, Sports manager Jimmy Dean said: “Connor is a proper player at the level and we’re delighted to have secured his services from @KTFCOfficial.
“He is another who captained his team last season, he’ll stand up in the tough moments, he’s a leader and he’ll be a top addition.”
Over the weekend, it was also confirmed that both Crawford and Brown have linked up with former Poppies boss Paul Cox at Boston United.
Glover has so far retained the services of Rhys Sharpe, Decarrey Sheriff and Saul Milovanovic while Lewis White and Ben Toseland have been confirmed as new signings.