Loder was the son of John Loder, 2nd Baron Wakehurst and his wife Margaret Tennant, daughter of Sir Charles Tennant, 1st Baronet. He was educated at Eton College and Cambridge University. From 1957 to 1966 he was employed by the Anglo American Corporation in Johannesburg and Lusaka. While in Johannesburg he helped run Union Artists, a black theatre group that played to mixed audiences in apartheid South Africa. In 1959 he founded the African Arts Trust, which supports black artists from South Africa.
When he returned to London, Loder became treasurer of the Institute of Contemporary Arts and later its chairman in the 1970s. From 1968 he was a Trustee and for 10 years chair of the Mental Health Foundation, for which service he was awarded the CBE in the 1989 Birthday Honours.
In 1980, Loder met Anthony Caro who was trying to organise an exhibition of British abstract art in South African townships. In 1981, when staying in New York State, the pair developed the idea of running workshops for professional artists, which became the Triangle Arts Trust. They held the first Triangle workshop in 1982 for thirty sculptors and painters from United States, the United Kingdom and Canada at Pine Plains, New York. The workshops became an annual event, and Loder later helped organise similar workshops in South Africa, Zimbabwe, Botswana, Mozambique, Zambia, Jamaica and Namibia. From 1990 he ran a workshop at Shave Farm in Somerset.
- "Robert Loder (1934–2017)". artforum.com. Retrieved 28 July 2017.
- "Person Page". thepeerage.com. Retrieved 28 July 2017.
- Geraldine Norman, "A collector who backs his own hunches: Trends mean nothing to Robert Loder. Abstract Expressionism was his great love and he wants us to share it", The Independent, Sunday, 31 July 1994.
- ""Robert Loder CBE" biography at Triangle Network". thetriangleconference.org. Retrieved 28 July 2017.
- "Anthony Caro biography". anthonycaro.org. Retrieved 28 July 2017.