The French/Swiss defender signed his contract with the club at Valley Parade this Friday afternoon. The deal also includes a further one-year option in the favour of the football club.
His arrival comes after the signings of Ben Williams, Mo Shariff, Matt Urwin and Filipe Morais earlier this week.
The 24 year-old had been on trial with the club for the last three weeks - featuring in the friendlies against Ossett Town, Blackburn Rovers, Bradford (Park Avenue) and Hartlepool United - before agreeing his City contract.
His move to the Coral Windows Stadium is subject to the defender receiving international clearance. The defender will need to receive international clearance before he can feature for Phil Parkinson's side.
He will wear shirt number 18 for the 2014/2015 campaign.
Born in Geneva, Switzerland, Routis joins City on a free transfer after leaving Swiss Super League club Servette earlier this summer.
Routis spent three years as a professional with Servette having played youth football with French side Libourne-Saint-Seurin earlier in his career.
Speaking about Routis' arrival, Parkinson said: "Chris has impressed us since coming to the club and we feel he will be a good addition the squad. He has the right attitude and we are looking forward now to working with him on a permanent basis."