The museum is home to the largest public collection of works by Henry Moore, most of which is held in the Henry Moore Sculpture Centre. The museum dedicated approximately of space to the sculptor, which includes the Henry Moore Sculpture Centre, and related galleries including the Irina Moore Gallery. Moore donated 300 pieces, nearly his entire personal collection, to the museum in 1974. The donation originated from a commitment made by Moore on December 9, 1968, to donate a significant portion of his work to the Art Gallery of Ontario, contingent that the museum builds a dedicated gallery to exhibit his works. In addition to the works donated by Moore, the museum also purchased another piece, "Two Large Forms", from the sculptor in 1973. The sculpture was originally placed at the museum's northeast façade, near the intersection of Dundas and McCaul streets. However, the museum later relocated the sculpture to Grange Park nearby in 2017 as part of the park's renovation.