The 32-year-old was found fatally knifed at lunchtime on Thursday on Thessaly Road, close to Battersea Power Station.
He was pronounced dead at the scene roughly 30 minutes after police were called.
Detective Chief Inspector Wayne Jolley, leading the investigation, said: “My thoughts are with Theo’s family and friends, at what is an unimaginable time for them.
“I have assured them that I and my team will do everything we can to bring those responsible for Theo’s murder to justice.
“Our investigation is progressing at pace and I want to ask for the public’s help in identifying the man in the CCTV image.
“I would ask anyone who recognises him to get in touch without delay. Likewise, anyone with any information about Theo’s murder should get in touch – even details that may seem irrelevant could be important to our investigation.”
There have been no arrests. Enquiries are ongoing.
Anyone who witnessed this incident or has footage should call police on 101 or Tweet @MetCC quoting 3633/24AUG.