US District Judge Paul Engelmayer also said the writer Christopher Wozniak infringed copyrights belonging to DC Comics, which employed him as a freelance artist in 1990 when he wrote The Ultimate Riddle, later retitled The Blind Man's Hat.
"We respectfully disagree with the court's decision and are considering our next steps," Wozniak's lawyer, Terry Parker, said in an email.
Wozniak claimed he was "stunned" to learn that The Batman was a near copy of The Ultimate Riddle, with the Riddler terrorising a Gotham City beset by crime and controlled by a corrupt banking cartel.
But in a decision handed down on Wednesday, Engelmayer said Wozniak intentionally and without consent lifted material from DC Comics' works to create his story, which "liberally exploits - indeed, is rife with" Batman characters and plot elements.
"The story's use of the Batman character and the surrounding protected elements is an act of clear and blatant copyright infringement," the New York judge wrote.
Engelmayer also said key similarities between the works - serial killers who are loners bent on destroying society, villains who taunt pursuers with "clues and riddles", and moments of "clarity or epiphany" that propel villains to crime - were too commonplace to support Wozniak's copyright claim.
For the latter, the judge in a footnote cited movies including Star Wars: Episode III - Revenge of the Sith, where Anakin Skywalker succumbs to the dark side of the Force and becomes Darth Vader.
Engelmayer also rejected Wozniak's "wholly speculative" claim for how Warner Bros might have gotten access to his story.
A lawyer for Warner Bros and DC Comics had no immediate comment.
Wozniak sued Warner Bros in October 2022. DC Comics, which has thousands of copyrights dating to 1941 for Batman works, sued Wozniak two months later.
The Batman starred Robert Pattinson as Batman, Zoe Kravitz as Catwoman and Paul Dano as the Riddler.
It received mixed to positive reviews, and grossed more than $US772 million ($A1.2 billion) worldwide, according to Box Office Mojo.
The cases are Wozniak v Warner Bros Entertainment Inc and DC Comics v Wozniak, US District Court, Southern District of New York, No. 22-08969.
