The 21-year-old won the Mike Turner Memorial Trophy for most promising young player at Albion last season and was the only Plymouth player to start every league match for the club.
Former England Under-18 international Porter, who has had previous spells at Birmingham & Solihull and Lydney, will challenge Matt Mullan and fellow new recruit Ceri Jones for a starting spot at Sixways next season.
Head Coach Richard Hill said: "George had a superb year in the RFU Championship and played almost every minute for Plymouth.
"He is very much the modern day prop and impressed Tevita Taumoepeau when we faced Albion during the season. He earned real respect off our front row and to get an endorsement off Tevita shows he is a real talent.
"While we are disappointed to see Callum Black leave us this season, we feel George is going to be a very good player for the Warriors and an ideal replacement for him."
Porter, who watched the RFU Championship final at Sixways, admitted he was relishing the prospect of playing top-flight rugby next season at the home of the Warriors.
"It was so exciting to be at Sixways to watch the final and I can't wait to be able to play in front of that kind of atmosphere," he added.
"It's a big opportunity for me at Warriors and I've seen firsthand this season how powerful the pack is.
"Working alongside experienced players such as Matt Mullan and Ceri Jones is something I'm looking forward to and I hope to make my mark.
"I will take some great memories away with me from Plymouth and the chance to develop under the guidance of Graham Dawe has been hugely beneficial. It's a great breeding ground for young players at Brickfields and I wish the club the very best for the future."