Construction on the West Block commenced by the end of 1859, at the same time as work on the Centre Block and Stent and Laver's East Block began. By the time it was completed in 1865, the building was three years behind schedule, and the first tenants were the offices of the Postmaster General, the Ministry of Public Works, and the Crown lands departments. As the number of parliamentary and administrative staff increased as the area of the country grew, more space was added to the West Block in 1878, the Mackenzie Wing and Tower, and in 1906, the Laurier Tower and link.

In the early 2000s, the masonry of the West Block was found to be in a state of severe disrepair; scaffolding and protective sheeting were erected in order to prevent falling blocks from striking pedestrians and/or cars below, and a restoration project was immediately implemented. The two largest towers were also stabilised with temporary steel structures, for fear of stones falling off them.

The West Block was emptied in January 2011, and, as a result, some of the core parliamentary functions that were housed in the West Block have been temporarily moved to other buildings, while others have been permanently relocated off-site. The West Block project, undoubtedly the most complex endeavor to date, is advancing as planned, is tracking on time to be completed in 2017, and on budget. Demolition and abatement are substantially complete, and exterior masonry rehabilitation is well underway.

During a planned renovation of the Centre Block to begin in 2019, the central courtyard of the West Block will be infilled and roofed over in order that it may serve as a temporary chamber for the House of Commons.