The capital's mayor Sadiq Khan confirmed the workers all died over the past few days.
Eight were bus workers, one worked for Transport for London and another worked for the London Underground.
Mr Khan told Sky News: "They are in my thoughts and prayers and my condolences to their families.
"We’ve got 25,000 bus drivers, more than 25,000 people working for Transport for London doing their best to keep public transport running for those essential key workers who need public transport to get from home to work and back home again – the NHS, those who work in our shops in the food sector, police, firefighters."
He said while record numbers of staff are off either because they are showing symptoms or are self-isolating, almost 90 per cent of buses and 55 per cent of Underground trains are running.
The news comes after the Unite union called on the Government to do more to provide personal protective equipment (PPE) and guarantee a safe working environment for transport workers.
Speaking about the deaths of five bus workers from Covid-19 last week, Unite and regional secretary Peter Kavanagh said: “Unite has been working continuously with Transport for London (TfL) and the operators to ensure the safety of drivers and others in the industry who are performing a heroic job in getting NHS and care workers to their places of work.
“These measures include deep cleaning of buses, additional cleaning of touch points, the sealing of screens around the driver, the provision of hand sanitiser for all and placing the passenger seating closest to the driver out of bounds.
“I have been in direct contact with the Mayor of London who shares our view that bus drivers must be fully protected."
Mr Khan said he has been lobbying government “almost on a daily basis” to get PPE for transport workers.
He said workers were currently using hospital-standard antiviral disinfectant regularly whilst cleaning during the course of the day.
But he added that Public Health England’s advice on them having no need to have PPE was “a cause of huge concern” for workers and their families.
"My key message to everyone is unless you really, really have to use public transport to get to work or back home, stay at home, work from home, and if you have to use public transport please avoid the rush hour." said Mr Khan.