Di is currently Chief Operating Officer, Company Secretary and administrator for the McElroy All Media group of companies, and is a joint shareholder.

Di began her career in 1965 as a secretary at the Queen Elizabeth Hospital in Melbourne. Within a year she became personal secretary to a leading Melbourne accountant and Member of the Victorian Legislative Assembly.

Next she joined a Management Consultant as Private Secretary to the Managing Director/Office Manager.

Then in 1969 Di joined the Australian Ballet as Office Manager and Secretary to the Administrator. She also acted as Personal Assistant and Secretary to Dame Peggy van Praagh and Sir Robert Helpmann, and the Chairman and Board of Directors. Her responsibilities included tour planning nationally and internationally, including tours to India, England, Russia and Romania, and the organisation of all first night functions and receptions. It was during filming of the ballet Don Quixote starring Rudolf Nureyev in 1972, that Di met her future husband, Hal.

In 1974 Di moved to Sydney to become Assistant Private Secretary to the then Federal Minister for the Media.

Finding the constant travelling burdensome, she joined Paradine Paterson Pty Ltd in 1975, initially as Secretary to its Managing Director, then production assistant. Her various assignments during this time included stage productions of Joseph and the Amazing Technicolour Dreamcoat and Sgt. Pepper's Lonely Hearts Club Band on the Road.

Di was headhunted to join the Interim NSW Film Commission in 1976 as Personal Assistant to the Chairman, and became the NSW Film Commission's first Project Manager.

In 1977 Di re-joined Paradine Pty Ltd (David Frost's company) as Production Co-Ordinator and Associate Producer on the pilot of Beauty and the Beast, a David Frost Special, the ninety minute John Denver Australian Special and six 90 minute Dave Allen Specials for the Nine Network.

In the late 1970's Di became a Partner/Director of Eden Productions Pty Ltd. In this capacity, Di was actively involved in script assessment, casting, location surveys, editing, publicity and marketing for Picnic at Hanging Rock, The Last Wave, Razorback and The Sum of Us, and the television productions Return to Eden (mini-series and series), The Last Frontier, A Dangerous Life, Which Way Home, A*mazing, Blue Heelers, Water Rats and Murder Call.

In 1996 she set up a new independent television production company called Di McElroy Productions to continue her writing career and develop television programs. She was joined by Hal in January 1998 when she folded her company into a new joint venture company entitled McElroy Television which was later rebranded McElroy All Media.

Di was Co-Executive Producer on the comedy series Dogs Head Bay (ABC, 1999), the drama series Above the Law (Ten Network/Columbia TriStar, 2000) and co-created and Executive Produced the drama serial Going Home (SBS, 2000 and 2001). She also co-created and Executive Produced Balmain Boys in 2001 for the TEN Network and Columbia TriStar, and co-created and Executive Produced the interactive topical drama series TwentyfourSeven (SBS, 2002). In 2003 Di was Creator/Consulting Producer on an American pilot of Bar Car (Showtime, 2003), based on the Going Home format. More recently Di was Creator/Consulting Producer on a pilot of The Bar for BBC3 in London, also based on the Going Home format.  In addition she licensed the Going Home format to Canada where Train 48 was a hit with 318 episodes ordered, and in France where as Le Train 163 episodes were ordered by Canal Plus.  In November 2006 Grundy Italia are producing 200 episodes with an initial order of 75 episodes of Andata e Ritorno (Round Trip) for RAIDUE, again based on the Going Home format.

Also in 2006 Di and Hal commenced production of a 13 x 1 hour action drama mini series they created  called Sea Patrol for the Nine Network in partnership with the Film Finance Corporation, Pacific Film and Television Corporation and Portman Media Assets.  Sea Patrol is about the Royal Australian Navy Patrol Boat service.  It premiered in July 2007and went on to run for five seasons and 68 episodes.