Route 19 began operating in 1906 between Highbury and Clapham Junction.
In 1934 route 19 operated from Finsbury Park to Tooting Bec station with a Sundays only extension to Streatham Common.
By 17 October 1956 the Sunday extension had been withdrawn between Streatham and Tooting, although it was reintroduced the following year on 1 May 1957 for a short period until its withdrawal on 16 October 1957.

On 23 January 1966, the route was once again given a Sunday extension, this time to Streatham Bus Garage and by 15 February 1969 the Sunday route was renumbered 19A, which was reverted to 19 by March 1971.
The Sunday extension was finally withdrawn on 8 January 1972.
Later that year, on 15 July, the Sunday service was cut back to Clapham Junction.
During August 1972, the AEC Regent III RTs were replaced by AEC Routemasters.
It was not until 5 October 1974 that the Sunday service reverted to Tooting Bec, following the withdrawal of route 19A. During 1975 garage journeys were extended to Tufnell Park, with the whole route being extended further to Archway by 1984.
On 3 August 1985, the route was withdrawn between Finsbury Park and Archway.

On 24 April 1993, route 19 became the first Routemaster operated service to be awarded to a company that was not a subsidiary of London Buses Limited following the route being awarded to Kentish Bus after a competitive tender.
Kentish Bus painted their Routemasters in a cream and maroon livery with route branding.
Following nearly five years with Kentish Bus, operation transferred to Arriva London South in January 1998, with the Sunday service operated by sister Arriva company Grey-Green.
A departure from the cream and maroon livery saw a return to the traditional London Bus red to comply with a contractual requirement for London buses to be 80% red.

A little over a year later, and after a period of 14 years, the Sunday allocation reverted to crew operation using Routemasters from Battersea.
The Brixton allocation was retained for some early and late journeys run off the N19.
In August 2002, in preparation for the introduction London congestion charge, the service was increased from 18 Routemasters to 26.
The extra buses were released from route 13.

On 2 April 2005 the route was converted to one man operation with 28 new Wright Pulsar Gemini bodied DAF DB250LFs.
Although Battersea was able to house all of the Routemasters needed to run the route, the newer and longer buses presented capacity problems, with six buses being outstationed at Norwood garage.

Upon being re-tendered, route 19 passed to London General’s Stockwell Garage on 31 March 2012 with new Wright Eclipse Gemini 2 bodied Volvo B5LHs and B9TLs.

On 28 March 2015, part of the route's allocation was transferred to Northumberland Park.
Route 19 was one of the routes used to test automatic speed-limiting technology, beginning in July 2015.

Upon being re-tendered, the route was won by Arriva London who resumed operating it on 1 April 2017.
 New Volvo B5LH/Wright Eclipse Gemini 3s are in use on the route.

New Routemasters cascaded from Route 48 were introduced on 12 March 2019.
Route 19 began operating in 1906 between Highbury and Clapham Junction. In 1934 route 19 operated from Finsbury Park to Tooting Bec station with a Sundays only extension to Streatham Common. By 17 October 1956 the Sunday extension had been withdrawn between Streatham and Tooting, although it was reintroduced the following year on 1 May 1957 for a short period until its withdrawal on 16 October 1957.
On 23 January 1966, the route was once again given a Sunday extension, this time to Streatham Bus Garage and by 15 February 1969 the Sunday route was renumbered 19A, which was reverted to 19 by March 1971. The Sunday extension was finally withdrawn on 8 January 1972. Later that year, on 15 July, the Sunday service was cut back to Clapham Junction. During August 1972, the AEC Regent III RTs were replaced by AEC Routemasters. It was not until 5 October 1974 that the Sunday service reverted to Tooting Bec, following the withdrawal of route 19A. During 1975 garage journeys were extended to Tufnell Park, with the whole route being extended further to Archway by 1984. On 3 August 1985, the route was withdrawn between Finsbury Park and Archway.
On 24 April 1993, route 19 became the first Routemaster operated service to be awarded to a company that was not a subsidiary of London Buses Limited following the route being awarded to Kentish Bus after a competitive tender. Kentish Bus painted their Routemasters in a cream and maroon livery with route branding. Following nearly five years with Kentish Bus, operation transferred to Arriva London South in January 1998, with the Sunday service operated by sister Arriva company Grey-Green. A departure from the cream and maroon livery saw a return to the traditional London Bus red to comply with a contractual requirement for London buses to be 80% red.
A little over a year later, and after a period of 14 years, the Sunday allocation reverted to crew operation using Routemasters from Battersea. The Brixton allocation was retained for some early and late journeys run off the N19. In August 2002, in preparation for the introduction London congestion charge, the service was increased from 18 Routemasters to 26. The extra buses were released from route 13.
On 2 April 2005 the route was converted to one man operation with 28 new Wright Pulsar Gemini bodied DAF DB250LFs. Although Battersea was able to house all of the Routemasters needed to run the route, the newer and longer buses presented capacity problems, with six buses being outstationed at Norwood garage.
Upon being re-tendered, route 19 passed to London General’s Stockwell Garage on 31 March 2012 with new Wright Eclipse Gemini 2 bodied Volvo B5LHs and B9TLs.
On 28 March 2015, part of the route's allocation was transferred to Northumberland Park. Route 19 was one of the routes used to test automatic speed-limiting technology, beginning in July 2015.
Upon being re-tendered, the route was won by Arriva London who resumed operating it on 1 April 2017.  New Volvo B5LH/Wright Eclipse Gemini 3s are in use on the route.
New Routemasters cascaded from Route 48 were introduced on 12 March 2019.
London Buses route 19