McCombe recently left York's League Two rivals Mansfield, despite only moving to Field Mill on a free transfer last summer.
He made seven appearances for the Stags and the 28-year-old is happy to have quickly secured a new club in the shape of York.
"I'm really excited," McCombe told the club's official website. "Obviously I'm glad to get it all done after working hard on it for the past week or so.
"I'm glad to be here and will be glad to be back playing football again. I'm someone who gives 100 percent which hopefully the fans will appreciate. I'm just a good defender and hopefully a good leader too."
York manager Nigel Worthington added: "The chairman and myself have worked hard over the last month or so to try and bring John into the football club.
"We had to wait until the start of January to see where things were at Mansfield and we're absolutely thrilled to have John come and join us.
"He's an experienced player at League Two level, has played a wealth of games and has captained Port Vale during their promotion season."