Tongan giant Taumoepeau is set for his 128th game in gold and blue and has become a rock in the home pack and huge favourite with supporters.
Horstmann stands on 130 games for Worcester and has been described as Mr. Dependable by boss Mike Ruddock for his performances for the club over the last five years.
"My heartiest congratulations go to Kai Horstmann and Tevita Taumoepeau on their 100th Premiership appearance. Both players have proven to be reliable and robust as well as skilful in their specific positions and they really are true Warriors," said Ruddock.