Victorian police officer Karla Challis's four-year-old daughter's dream of becoming a princess has been granted, now her mum has been crowned a Moomba monarch.

Acting Sergeant Challis says she feels very fortunate to assume the Moomba throne along with six other representatives from the state's community and emergency services.

She said her daughter Wynter would be glad to learn she's now part of a royal family, but she wasn't sure if she'd be allowed to take the Moomba crown home.

"It might have to go into archives, I think," she said.

Seven representatives from Ambulance Victoria and St John Ambulance, Salvation Army, MFB, CFA, Department of Sustainability and Environment (DSE) fire management division, State Emergency Service and Victoria Police will lead this year's parade as the reigning Moomba kings and queens.

Melbourne Lord Mayor Robert Doyle said he was proud the city could honour its unsung heroes.

"This year we have decided to honour people and organisations who are on the front line, who serve and protect our community every single day," he said.

Mr Doyle said organisers were grappling with the challenge of fitting seven adults on a single float.

Representing DSE's firefighting division, Stephanie Carr said the honour was welcome good news after the deaths of two Victorian firefighters last week.

"Obviously it's been a hard year ... it was a tragedy, and it sort of ricochets through the department, but we're out there and we'll continue to do our work," she said.

The free annual festival is held over the Labour Day long weekend (March 8-11) in Melbourne, with popular events include the Birdman Rally and Moomba parade.