One Bloor West

One Bloor West, also known as The One, is a supertall skyscraper currently under construction in Toronto, Ontario, Canada. If completed, it will be the tallest building in Canada. At a revised 308.6 metres (1,013 feet) and a revised 85 storeys, it will be taller than First Canadian Place, which has been Canada's tallest building since 1975. It will also be Canada's first supertall (> 300 m) skyscraper, as defined by the Council on Tall Buildings and Urban Habitat. Construction of the building is estimated to be completed by 2028.

Located in Toronto's Yorkville neighbourhood at the intersection of Yonge Street and Bloor Street, One Bloor West is across the street from the 257-metre-tall (843 ft) One Bloor condominium building. It will also stand next to Two Bloor West, an existing skyscraper completed in 1972. The site of The One involved land assembly that includes properties at 768 Yonge Street, in addition to those at 1 and 11 Bloor Street West.

Developer Sam Mizrahi acquired the land in October 2014 for CA$300 million. Mizrahi received approval from the city to build on September 12, 2016. The total cost for the project was estimated to be $1 billion during planning stages, but that figure had ballooned to $2 billion at the time of the receivership filing in October 2023.