Sir James began collecting New Zealand art in the mid-1960s. In 1992 he transferred his collection to the James Wallace Arts Trust. The Trust now has more than 7000 works housed in the Pah Homestead in Auckland, a cultural resource for present and future generations. He also established the Annual Wallace Art Awards. The longest surviving and richest annual art awards in Australasia, amounting to over $160,000 and including artist residencies in New York and Switzerland.

Sir James Wallace is a founding patron of the Arts Foundation and a founding trustee of various charitable trusts, including being the founding underwriter of the Auckland Chamber Orchestra and founding patron of the Auckland Theatre Company, NZ Opera, NZ Ballet, and a member of the board of the Auckland Philharmonia.