Lewis Hamilton -- I've Got Kendall Jenner's Back Again ... at Fashion Week (PHOTO)

Lewis Hamilton took a Rihanna detour (it's the thing to do, after all) ... but ended up right back with Kendall Jenner -- 'cause they were spotted out in NYC together looking pretty cozy.

The Kendall/Lewis rumors started swirling earlier this year when she was walking around the Monaco Grand Prix wearing what looked like his chain.

But then hurricane Rihanna started blowing in August, and it sure as hell looked like Lewis had moved on ... but you know how RiRi romances go.

Cut to NYC ... where it's now Fashion week. It's a huge event for KJ, so it's interesting that Lewis is hanging with her again. Kinda like when she showed up in Monaco for him.