Originally a residential area, much of the northern portion of the Flats is now occupied by the Canadian War Museum and the National Holocaust Monument.

In 1820, LeBreton lived at the community of Britannia, west of Ottawa and overheard Lord Dalhousie explain that the intended plan for the Rideau Canal was from Dow's Lake to the Chaudière Falls, directly crossing the flats.

[6] For his part, LeBreton vigorously maintained that he had purchased the land fairly at a public auction and that he had been grievously wronged by Dalhousie and those in the community who took the Governor General's side.

LeBreton claimed he was one of the few to grasp the commercial value of the flats and that he had begun to make offers to acquire land there as early as 1818, well before the canal was approved or any route revealed.

[7] By the mid-19th century, LeBreton Flats developed into a mixed community to serve the lumber mills on the nearby Chaudière and Victoria islands.

The area was rebuilt, but the lumber barons relocated their dwellings up into the city proper above the escarpment, leaving the workers as the remaining Flats' residents.

This situation was remedied with a federal agency called the National Capital Commission (NCC) acquiring all title to the land.

The portion of Lorne Avenue which lies below Nanny Goat Hill is an example of the housing which filled LeBreton prior to the 1960s and is a Heritage District designated by the City of Ottawa.

[12] The portion of LeBreton Flats that had been expropriated and left vacant in the 1960s welcomed its first residents in 2008, as the first condominium building constructed in the first phase of the redevelopment neared completion.

[13] In 2015, the NCC put out a request for submissions to redevelop the south and south-western sections of LeBreton Flats, north of Albert Street, 21 hectares (52 acres) in size.

The NCC then conducted a new series of public consultations which resulted in a new Preliminary Master Concept Plan[15] being approved in January 2020.

Due to anticipated failures, the City of Ottawa filed an Application to Alter and make repairs to five other stone arch bridges in the area in 1999.

The Ottawa River Runners made the Tailrace into a Class 2 whitewater course with natural and artificial obstacles for competitions and practice.

[23] In 2022, the main Canada Day stage show, traditionally held on Parliament Hill, was moved to the park due to the ongoing renovation project at the Centre Block.

[24] In 2023, a sculpture called When the Rubber Meets the Road by Gerald Beaulieu was installed by the National Capital Commission on a bike path in LeBreton, near Pimisi station.

The sculpture, which depicts a run-over crow, is 5 metres long, weighs 360 kilograms and is made of 50–60 recycled tires.