Cross, former captain of Edinburgh Rugby, has established a reputation as one of the most talented young coaches in Scotland since his retirement from playing.
The 32-year-old has been a crucial part of the Scotland Under-20 set-up as Defence Coach and was also involved with coaching Glasgow Warriors during Scotland's autumn and Six Nations internationals.
Cross has also been Head Coach at Edinburgh Accies for the last three seasons, guiding them to the top-flight of Scottish rugby in the 2010/2011 season and fourth place in the RBS Premiership in 2012/13, earning a place in the British & Irish Cup.
A former flanker during his playing days, Cross will move to Sixways to link up with Director of Rugby, Dean Ryan, who was alerted to his progress while working as Scotland's Forwards Coach.
"Simon has a strong point to prove and is an ambitious young coach," said Ryan. "Developing coaches is as much a priority as the players here and we are delighted to welcome Simon to the team at Warriors.
"Hoggy (Carl Hogg) knows Simon very well from his Edinburgh days and we have seen enough potential in him to really know he will make a very positive contribution at Warriors."
Cross described the move south of the border to link up with Warriors as a 'huge opportunity' in his career.
"I'm joining a dynamic coaching group and it will be fantastic to work with them and such a motivated squad of players," said Cross.
"I know Carl well, he coached me for a number of years, and I'm looking forward to that link up and working with Dean (Ryan) and Shane (Howarth).
"To leave my roles in Scotland was difficult as I have enjoyed it immensely, but this is a huge opportunity for me that I plan to take. I would like to thank all the players, fellow coaches and club officials I have worked with for the support they have given him and wish, in particular, Edinburgh Accies all the very best for the future."