The man, aged in his thirties, was arrested at an address in Leeds at 8am this morning on suspicion of the theft of the plaque, which was taken from Leeds Bridge on Monday, April 25.
He remains in custody and enquiries are ongoing.
Police say they are aware that an earlier arrest has been highlighted over the weekend and can confirm that another man was arrested on April 28 on suspicion of the theft of the plaque following information received.
He was later released under investigation.
A further suspect was also identified on April 28, and arrest enquiries for him remain ongoing.