In 2009, it was announced that the museum received a donation from American businessman Julian Robertson, valued at over $100 million, the largest ever of its kind in the region.

Following pressure by such eminent people as Sir Maurice O'Rorke (Speaker of the House of Representatives) and others, the building of a combined Art Gallery & Library was made necessary by the promise of significant bequests from two major benefactors, former colonial governor Sir George Grey and James Tannock Mackelvie.

The Grey bequest includes works by Caspar Netscher, Henry Fuseli, William Blake and David Wilkie.

The Mackelvie Trust continues to purchase art works to add to the collection, which now includes significant 20th-century bronzes by Archipenko, Bourdelle, Epstein, Moore and Elisabeth Frink.

Her gifts in 1948 and 1950 totalled 154 works by modern British artists, including Christopher Wood, Frances Hodgkins, Phelan Gibb, R. O. Dunlop and Alfred Wallis.

In 1953 Rex Nan Kivell donated an important collection of prints, including work by George French Angas, Sydney Parkinson, Nicholas Chevalier, and Augustus Earle.

The Auckland Art Gallery Toi Tamaki have also collaborated in joint purchases including Michael Parekowhai's The Indefinite Article[4] in 1990 and Giovanni Intra's Untilted (Studded Suit)[5] in 2003.

[12] More recently Dame Jenny Gibbs has marked a number of occasions through gifting including Gordon Walters 1971 painting Genealogy 5 in tribute to the Directorship of Chris Saines in 2022[13] and No Ordinary Sun by Ralph Hotere in memory of the artist in 2013.

The donation included works by Paul Cézanne, Paul Gauguin, Pablo Picasso, Henri Matisse, Piet Mondrian, Salvador Dalí, Georges Braque, André Derain, Fernand Léger, Pierre Bonnard and Henri Fantin-Latour, and was the largest of its kind in Australasia.

"It is a fantastic opportunity to share with the rest of the world some of the best of our New Zealand and international collection", said RFA Gallery Director Chris Saines.

Auckland Art Gallery has contributed 85 artworks to the project: 56 are from its New Zealand Pacific collection and 29 by international artists.

Several artists maintained studio space in the complex during the period just after the war;[clarification needed] the weaver Ilse von Randow utilised the clock tower rooms and created onsite the Art Gallery Ceremonial curtains, executed as part of the 1950s modernisation.

[20] In the late 2000s, a major extension was mooted, which drew substantial criticism from some quarters due to its cost, design and the fact that land from Albert Park would be required.

[26] The library holds approximately 160 archival collections, including records for different galleries in New Zealand and personal papers of artists.

The 1956 Spring Exhibition 'Object and Image' showed works by modern artists such as John Weeks, Louise Henderson, Milan Mrkusich, Colin McCahon, Kase Jackson and Ross Fraser.

Tomory's intended purchase of Hepworth's Torso II in 1963 (likened by one councillor to 'the buttock of a dead cow') changed the climate of art and culture in New Zealand.

In 1981 Rodney Wilson was appointed as the Auckland Art Gallery's first New Zealand-born director and, still in 2024 the only New Zealander to hold the position.

Other achievements during his incumbency were the funding and development of the New Gallery for contemporary art, which opened in 1995, the establishment of Haerewa, the Maori Advisory Group and a significant range of acquisitions for the collection and the Mackelvie Trust including works by including works by Vanessa Bell, John Nash, John Tunnard, Anish Kapoor, Jesus Rafael Soto and Ed Ruscha.

The E.H. McCormick Research Library, Auckland Art Gallery Toi o Tāmaki maintains a complete exhibitions list from June 1927.