The Magpies were previously under embargo for failing to make required payments to Revenue & Customs and other clubs, but new owner Alan Hardy confirmed that this was no longer the case last week.
Yeates, 32, joins from fellow League Two side Blackpool, for whom he has featured 20 times this season.
The Irishman told the official Notts website: "I'm over the moon. When I got told about the interest it was a no-brainer for me. I know a few of the lads in the dressing room and that'll probably make it easier to settle in.
"I just want to get on the ball and try to make things happen - whether that be behind the front man or from out wide. I've always been about trying to make chances and I try to chip in with the odd goal when I can."
Yeates has made 384 career league appearances for a host of clubs including Sheffield United, Watford and Bradford City.