Cummings was born in 1927, in Adelaide, South Australia, the son of the accomplished Irish-born trainer Jim Cummings, who trained the great stayer Comic Court to a win in the 1950 Melbourne Cup. Bart started his career working for his father as a strapper, despite being allergic to horses and hay. Cummings had an older brother, Pat, and said of his father; "I had the best of teachers. My dad had a lot of experience behind him and I picked up from him by watching, listening, and keeping my mouth shut".

Cummings received his trainer licence in 1953, and set up stables at Glenelg in South Australia. His first significant win came in 1958, when he won the South Australian Derby, his first Group 1 win.

Cummings had a record total of 89 runners in the Melbourne Cup starting in 1958 with Asian Court who finished twelfth. His next entrant was Trellios who fronted up in 1959 and finished fifth. In 1960, Sometime finished in sixth place. It wasn't until 1965 that, with three runners in the Melbourne Cup, Cummings finished first with Light Fingers and second with Ziema, with his other Runner, The Dip, finished eighteenth.

In 1965, 1966, 1974, 1975, and 1991, Cummings trained both the first and second placed horses in the Melbourne Cup.

In 1968, Cummings opened stables, now called Saintly Lodge, at Flemington in Melbourne, home of the Flemington Racecourse. Later that year, he won the Trainer's Premiership the first of five.

In 1969, the favourite for the Melbourne Cup was Cummings' horse Big Philou, which had already won the Caulfield Cup. However, the horse was drugged illicitly with a large dose of laxative the morning of the race and was unable to compete.

In 1974 he became the first trainer in the British Commonwealth to train horses who won $1 million in prize money.

In 1975, Cummings moved his operations to a new facility near Randwick Racecourse in Sydney, called 'Leilani Lodge'.

In the late 1980s, Cummings spent millions of dollars purchasing racehorses, much of the money spent on behalf of a tax minimisation syndicate. Unfortunately, like many other trainers Cummings was hit hard by the recession of the early 1990s. With help from Reg Inglis' organisation, however, he avoided bankruptcy and continued training.

1982 Made a Member of the Order of Australia for his services to the racing industry.

1991 11 December 1991, Cummings was inducted into the Sport Australia Hall of Fame.

1997 Named in National Trusts 100 Australian Living Legends (chosen by a national vote)

2000 Awarded a Centennial Medal and carried the Olympic Torch

2001 An inaugural inductee into the Australian Racing Hall of Fame .

2004 First licensed person to be made Lifetime member of Victoria Racing Club

2007 Australia Post placed his image on a postage stamp as part of its Australian Legends series.

2008 Racing NSW announced a new horse racing award to be known as The Bart Cummings Medal which will be awarded for 'consistent, outstanding performances amongst jockeys and trainers at New South Wales metropolitan race meetings through the racing season.

Cummings had training facilities at Randwick (NSW) and Flemington(Vic) but in 2014 the Flemington stables closed and all horses and training moved to Randwick. Cummings had gone into virtual retirement at Princes his property at the foot of the Blue Mountains. Bart's grandson and partner, James made the decision for financial reasons.

Cummings died on 30 August 2015 in Prince's Farm in Castlereagh NSW, two days after he and wife Valmae celebrated their 61st wedding anniversary. He was 87. His family accepted an offer by the Premier of New South Wales, Mike Baird, of a state funeral, which took place on 7 September at St Mary's Cathedral, Sydney, on College Street, and was televised on Sky Thorougbred Central, 7Two, ABC and Nine Network Australia from 10AM AEST.

In November 2016 two sisters in Adelaide, Kimberley and Julia Mander went public with a claim that Cummings was the father of their father, Peter Mander, from a relationship with their grandmother, Patricia Kilmartin. They allege that the couple were in a relationship for over a year and Patricia fell pregnant in mid-1951. The relationship ended and Lloyd Mander married Patricia and raised Peter as his son. They have engaged a Lawyer and have asked for DNA tests for to confirm their story. They have stated that they are not interested in a financial claim on Cummings' estate.

Mediation will be under the control of eminent former appeal court judge Keith Mason, QC with the first meeting is scheduled for November 30. The mediation over two days failed to resolve the dispute and Judge Philip Hallen ordered that the parties submit any further evidence by 30 January. A hearing was scheduled for 24 February when a date for a hearing will be set. With the death of Barts wife in early January 2017 the family "...will put aside all ill-will as the mourn the loss of their mother". No further stories regarding the estate have appeared in the media and the matter may have been settled privately.