Mr Gross is suing for at least $200m (Â£140m) he claims he lost after being forced to leave Pimco in 2014.
The bond manager alleges that executives at his former firm plotted to oust him and spilt his bonus.
A judge ruled there was enough evidence to proceed pointing to a "series of alleged oral promises [and] assurances of continued employment."
Pimco had argued Mr Gross was never guaranteed employment and could have been fired without cause at any time. The company hasn't commented on the latest development.
Mr Gross helped found Pimco - an investment management company that focused on bond investing - nearly 40-years ago.
He left the firm abruptly in 2014 following disparaging reports about his management style.
Mr Gross filed his lawsuit against Pimco in October.
Investor Bill Gross can move forward with a lawsuit against his former company, Pimco, a judge has ruled.