The 29-year-old only joined the Sky Bet League One outfit in the summer and made five appearances but requested a release from his deal to attend to personal issues in his native Scotland.
He pens a two-year deal with the Staggies, with the option of a third, returning to the club where he spent last season.
Shrews boss Micky Mellon told the club’s official website: “Unfortunately Martin has had to return to Scotland due to a personal reasons to do with his family.
“It is sad that he has had to return home but sometimes that is the way things go in life, never mind football.
“He came to see me last week and explained his reasons and there is no way the football club could stand in the way of his decision and wish him all the best in the new chapter of his career at Ross County.”
Ross County manager Jim McIntyre added: “We are delighted to have signed Martin Woods on a permanent deal just before the end of the transfer window.
“Martin was instrumental in the great run of form that this club enjoyed in the second half of last season so we know what he is capable of and it is great news to have been able to get him back to the club on a long-term contract.
“When we learned Martin would be open to a move back to Scotland we didn’t hesitate in putting a deal in place for him.
“Martin will add more quality and bring competition for places to the squad and I know he is looking forward to coming back to Dingwall on a permanent deal. I’m sure the fans will also be looking forward to seeing him in action again at the Global Energy Stadium.”
Meanwhile, Staggies loanee Daniel Bachmann has returned to parent club Stoke after having his deal terminated early.