Andy Burnham has promised to curb companies' ability to restrict what their workers can do after leaving their job.
In a speech, the prime minister said the use of non-compete clauses in employment contracts had "gone too far" and was holding innovative UK companies back.
He added the clauses had forced workers to go without pay after leaving a role, as well as making it harder for growing firms to hire new staff.
Ahead of the Budget later this month, he also said there was "more to do" on tax to encourage promising firms to stay in the UK.
Sir Keir Starmer's government had been exploring possible restrictions on non-compete clauses since late last year, including a total ban, banning them above a certain salary threshold, or limiting how long they can last.