The right-back has joined the League Two side on a permanent basis, penning a contract until the end of next season.
Baker, who is 23 years old, had fallen down the pecking order in the Championship with Sheffield Wednesday and has been allowed to leave this month.
He joined the Owls in January 2017 having previously been on the books at Cardiff City and went on to make 12 first team appearances for the Yorkshire side.
The Wales Under-21 international has not featured for Wednesday this season under Garry Monk and will be looking forward to a fresh challenge at Rodney Parade.
Baker has said, as per the Exiles’ website: “As soon as I found out there was interest, it was a no brainer for me to come back home to Wales and accept this great opportunity. I enjoyed my time at Sheffield Wednesday, but it was time for me to move on and as soon as I heard the interest from the Gaffer I was straight on to my agent trying to get the deal sorted straight away.”
“I’d like to say I am hard-working and love to get up and down the pitch. I can’t wait to get going.”
Baker has been handed the number 12 shirt by Newport and is in contention to make his debut for them when they take on table toppers Swindon Town at home this weekend.