The Manager's Co., Gotham NYC Entertainment, filed the suit today ... claiming the Situation dumped Gotham back in May for what he deemed a "lack of performance."
Gotham denies any poor performance -- but even if there was ... the lawsuit claims Sitch was contractually required to give Gotham 30 days notice ... and a chance to correct any issues.
Gotham claims it never got that opportunity -- and therefore Sorrentino is in breach of his contract.
In the suit, Gotham says it's managed Situation since the 2009 premiere of "Jersey Shore" -- and it not only discovered Sitch, but transformed "his career from relative obscurity to become an international celebrity."
Gotham is suing for damages in excess of $1 million.
- The Situation: I MIGHT Be Ditching 'Jersey Shore'
- Vinny -- Goodbye 'Jersey Shore,' Goodbye Career!
- 'Jersey Shore' Guys -- Man Down