The powerful 21-year-old centre made his Guinness Premiership debut for Warriors in April 2009 when he faced Harlequins at The Stoop.
King, who has represented England at Under 18, Under 19 and Under 20 level, was also named in the Worcester line-up on the opening day at the current season and impressed with an all-action display and his part in the opening try of the game for Miles Benjamin.
Director of Rugby Mike Ruddock said: "It's great news that Greg has signed up for two more years at the club.
"He is a hard working and hard running centre with a huge amount of potential to develop into a very strong candidate for a starting berth at the club over a longer period.
"Greg showed his maturity in the first game of the season against Northampton Saints when he performed admirably and underlined his potential that day with a very solid display."
Greg King said: "It's a good place to be and so I'm really pleased to have signed."
"It was great to get a game against Madrid last weekend and also my first try for the Warriors, prove what I can do and hopefully I can now get a chance against Montpellier.
"I have strong connections with the club and have come from a very strong Academy.
"I'm here with a lot of players that I have been around for a long time, we have grown up together and now want to follow it through and get a slot in the first team.
"I feel like this is the right place for me to continue to develop. I have great people to learn from with the coaching staff and also experienced guys like Sam Tuitupou and Dale Rasmussen, they are always there to talk to and work on things to develop my game even further.
"You only have to look at someone like Alex Grove to see the route forward, what he has done is incredible with the progress he has made in such a short period of time.
"Hopefully I can mirror that and my goals are now showing my worth to Warriors and being part of a successful period for the club in the years to come."
