It comes after Lively filed a legal complaint against Baldoni in December, alleging sexual harassment and that he had campaigned to “destroy” her reputation.
Now, Baldoni has responded by suing for $400m (£326m) damages on claims of civil extortion, defamation and invasion of privacy, according to US media.
Representatives for Lively, Reynolds and their publicist, who is also named in the case, are yet to respond to Baldoni’s lawsuit.
In the latest step in their bitter legal battle, lawyers for Baldoni, 40, has claimed Lively and her team made a “duplicitous attempt to destroy” him.
His attorney Bryan Freedman said the actress and her partners had disseminated “grossly edited, unsubstantiated, new and doctored information to the media”.
He also said Lively and her team had “attempted to bulldoze reputations and livelihoods for heinously selfish reasons”.
The dispute stems from the production of It Ends With Us, which was adapted from a novel about domestic abuse by Colleen Hoover.
Released last August, the film was a box office success, bringing in more than $350m (£280m) globally.
But it appeared on the press tour that all was not well between the co-stars, who were not pictured on the red carpet together during the premiere in New York, with Baldoni skipping one in London altogether.
