With a high level of training behind her, Farrell broke into the women's satellite tennis circuits during the 1970s in Brazil and England and played in qualifying tournaments for the U.S. Open and French Open in singles and also played in qualifying rounds for Wimbledon doubles, coming within one match of playing against Chris Evert. She played on the United States Tennis Association (USTA) satellite circuit and the Avon Futures Tour, touring the U.S. and Canada. Farrell finished in the top 10 of the Nike Circuit and reached the Masters doubles finals in Saratoga. In 1989, she was the runner-up in the National 30 Indoors Tournament and won the Arthur Ashe Tennis Classic at Flushing Meadow. Her highest international ranking was 202nd in 1980 and was ranked 237th in the Woman's Tennis Association (WTA) back in 1983.
In 1989, she was ranked second in the Eastern Tennis Association's singles open and earned a third-place ranking in the nation in the Singles 30 Division of the United States Tennis Association. She also captained the Western New York Regional Team and in 1990, she was named to the Sears Cup team for the Eastern Tennis Association.
In 1994, Farrell was ranked ninth in the 35s Open Singles and No. 14 in doubles with Shelby Torrance of Corpus Christi, Texas, and has played in the annual National 35s tournaments in Philadelphia and Phoenix. She has also competed in the Chautauqua County Adult Tennis League.
She came home to Dunkirk to work for her family's construction and roofing business after "retiring" from professional tennis, but has remained involved in the sport to this day. Farrell was elected to the Buffalo Tennis Hall of Fame in 2006.