Harrington was born in London. Her father was Brigadier Bryan Fowler, an officer in the British Army, and her mother was Mary Walford. Bryan Fowler was originally from Kells, County Meath and served with the Royal Artillery in both World Wars, and married Mary, who was a widow, in 1944. She had two children from her previous marriage. Harrington had an older brother, John Fowler, who was also a racehorse trainer and died in an accident in 2008. Bryan Fowler left the army in 1949 and returned with his family to Ireland where Harrington spent her childhood. She did not go to school until she was aged twelve, being tutored. She then went to school at Hatherop in England for four years before going to a Finishing school in France. Harrington and her husband Johnny Harrington both shared a love for horses. She was married to him until his death from cancer in April 2014. Johnny owned a racehorse and was a bloodstock agent. Together the couple had four children: James and Tara and Johnny's from a previous relationship; Emma and Kate. As well, Jessica and Johnny had three sons-in-law, a daughter-in-law and seven grandchildren.
Professional life
Even before Harrington got her training permit in 1989, she had earned a reputation for being one of Ireland's top three-day event riders. She represented her country with credit on three levels: European, World and Olympic. In 1994, Harrington's horse Oh So Grumpy earned himself a “landmark success” at the Galway Hurdle. A couple of years later Dance Beat picked up Leopardstown's Ladbroke Handicap Hurdle. By 1996 Harrington had earned a reputation for being linked to high-profile horses. She then went on to enjoy seven Cheltenham Festival victories, rendering her "one of the most successful current Irish trainers at the meeting." Her most notable horses include: Moscow Flyer, Curtain Call, Bible Belt, Pathfork and Laughing Lashes. On 17 March 2017 she won the Cheltenham Gold Cup with Sizing John. Exactly one month later on 17 April Harrington won the Irish Grand National at Fairyhouse racecourse. It was a first win, in both races, for both Harrington and local rider Robbie Power.
Wins
Over the years Harrington earned a reputation on the Flat. On September 2010 Pathfork won the National Stakes.
