Officers say the theft happened on New Year's Eve at the Quwwatul Mosque in Deepdale.
A man was captured on camera entering the building in Peel Hall Street at around 11:30am, before leaving two minutes later.
It was subsequently discovered a charity box containing around £200 was missing.
A spokesman for Preston Police said: "We are issuing an appeal to identify this man in connection with a theft.
"The male entered the mosque at 11:30am and left within two minutes, a charity box with approximately £200 inside was stolen.
"Officers would like to speak to this man with regards to the theft.
"If you know who he is, please call 101 quoting -0884 of the 31st December 2021."