Director of Rugby has hailed the news that 'Mr Dependable' in the pack wants to remain at the club beyond his current deal, that was due to run out at the end of this season.
And Horstmann has spelled out why he committed to Worcester and the big plans for the future at Warriors.
"I'm really pleased to sign. I'm settled and have enjoyed my career at Sixways and look forward to a bright future and continuing to help the club achieve its big ambitions," he said.
"I want to be a part of something special and feel that is what is happening at Warriors. I've seen the club come through some dramatic experiences in the past and in the Guinness Premiership, but now feel we are ready to move on into the top half and challenge the top sides.
"I feel I have become a better player at Warriors. I've improved many aspects of my game and really enjoy working with the current coaching set-up who I feel can push me even further. The structure is there for me to progress.
"My aim remains to play a big part at Warriors and also push my international claims. I've big aspirations in the game and want to play for England. That is something I feel I can achieve with Warriors.
"From the start I've told the coaching staff I wanted to stay. I can't see myself playing for any other team and couldn't be happier to sign the new deal."