Private renters in the capital can use the system to check if their landlord or agent has been prosecuted or faced civil enforcement action for housing offences.
Tenants will also be able to report landlords they suspect of unscrupulous practices.
And there will also be records from the three national organisations offering a free and independent service for resolving disputes with their landlords.
The mayor said the database will give Londoners more confidence when renting a home and act as a deterrent to landlords and letting agents who behave dishonestly.
He called for a publicly accessible national version, as ministers plan to develop a database that can only be accessed by the relevant authorities.
The mayor’s database has now been populated from records of the fire service and 10 boroughs, including Camden, Islington, Kingston, and Westminster, covering around a quarter of renters living across the city.
A further eight boroughs including Croydon, Hackney and Tower Hamlets have agreed to submit records in the coming weeks.
Khan said he hopes all other London councils will soon add their data to help protect tenants living in their boroughs.
Nowhere to hide
The mayor said: “Many landlords and agents across London offer a great service – but sadly some don’t.
“My new database is about empowering Londoners to make informed choices about where they rent, and sending rogue operators a clear message: you have nowhere to hide.
“Boroughs on the database and I are using our existing powers to help London’s renters – but to go much further we need investment and resources from central government.
“For a start they should stop dragging their feet on the creation of the compulsory national database they promised to set-up.
“Before Ministers have even laid the regulations for their database, we’ve planned, built and launched ours – and unlike the Government’s plans, we have made our database accessible to the public.”
London Fire Brigade’s assistant commissioner for fire safety, Dan Daly, said: “From overcrowded housing to poor escape routes and badly maintained fire doors, our fire inspectors regularly find homes that are just too dangerous to live in.
“Making it easier for tenants to find out if a potential landlord has flouted fire safety rules will act as a deterrent for the small number of dishonest landlords who pose a large risk to their tenants.”