The Thursday arrest comes after what police called an "unbelievably audacious" theft from a museum in Offenburg, southwestern Germany - the latest in what appeared to be a spate of similar robberies.
"The person who is strongly under suspicion is accused of having been involved in the theft of the horns in Offenburg," a statement by the town's police said.
Police said two people distracted staff at the Offenburg museum while another two climbed on the display case, removed a rhino head from a wall and smashed off the horns with hammers.
Rhinoceros horn is especially prized in Asia where many consider it to have aphrodisiac and disease-fighting properties.
The suspect, together with two other Britons, was initially apprehended at the end of February in the southern city of Munich after being stopped in a car that had been stolen in Britain, a police spokesman said.
He was held pending extradition, but police noticed a resemblance to sketches of the suspected rhino horn thieves and further investigation led to the arrest, the spokesman said.
The other Britons are still awaiting extradition but inquiries against them are continuing, he added.
Similar thefts have occurred throughout Europe, with some museums taking the unusual step of replacing their rhino horns with fake ones to deter robberies.
Rhino horns can fetch between €25,000 and €200,000 depending on their size.