Farnworth began her professional career in 2007 when she joined her hometown team, the Christchurch Sirens, of the Women's National Basketball League. She played one season for the Sirens before the club folded prior to the start of the 2008–09 season. In 2009, Farnworth moved to Australia and joined the Albury Wodonga Bandits of the South East Australian Basketball League. In 21 games for the Bandits in 2009, she averaged 15.1 points and 7.3 rebounds per game. Farnworth returned to the WNBL for the 2009–10 season, joining the Dandenong Rangers. In 22 games for the club, she averaged 5.0 points and 2.2 rebounds per game. After spending the 2010 SEABL season with Albury Wodonga, Farnworth joined the Bendigo Spirit for the 2010–11 WNBL season. In 24 games for the club, she averaged 4.3 points and 2.8 rebounds per game. Following the 2010–11 WNBL season, Farnworth joined the Bendigo Braves for the 2011 SEABL season. In July 2011, Farnworth signed with the Adelaide Lightning for the 2011–12 WNBL season. In 24 games for the club, she averaged 4.2 points and 2.4 rebounds per game. Following the 2011–12 WNBL season, she joined the Hume City Broncos for the 2012 Big V season. In 12 games for Hume City, she averaged 20.9 points, 8.5 rebounds, 3.1 assists and 1.4 blocks per game.
In August 2012, Farnworth signed with the West Coast Waves for the 2012–13 WNBL season. Edmondson found her place with the Waves in Perth while playing under her long-time coach and mentor Kennedy Kereama. However, success eluded the Waves over her three seasons with the club as they finished on the bottom of the ladder every year, winning just nine total games over that span. Her best season with the Waves came in 2013–14 when she recorded averages of 13.2 points, 4.1 rebounds and 2.4 assist per game, all career highs. During her time with the Waves, she played in the State Basketball League during the off-seasons, competing with the Willetton Tigers and Joondalup Wolves.
On 2 September 2015, Farnworth signed with the Perth Lynx for the 2015–16 WNBL season, joining the rebranded club after the Perth Wildcats purchased the West Coast Waves. She helped the Lynx reach their first WNBL Grand Final since 1999, where they lost the best-of-three series 2–0 to the Townsville Fire. She appeared in all 27 games for the Lynx in 2015–16, averaging 3.7 points, 2.1 rebounds and 1.4 assists per game. For the 2016 SBL season, Farnworth joined the Perry Lakes Hawks. On 3 May 2016, Farnworth re-signed with the Perth Lynx for the 2016–17 WNBL season. She started all 27 games for the Lynx in 2016–17, averaging 8.8 points, 3.6 rebounds and 2.4 assists per game. In March 2017, Farnworth re-joined the Perry Lakes Hawks. Farnworth was a powerful force for the Hawks in 2017, helping them win the minor premiership with a 20–2 record before reaching the SBL Grand Final. Farnworth took out the Grand Final MVP award after her dominant performance in leading the Hawks to championship victory over the Mandurah Magic, particularly in the second half where she had 18 of her 26 points. She shot 8-of-18 from the field, 3-of-7 from downtown and 7-of-8 at the foul line. On 11 April 2017, Farnworth re-signed with the Perth Lynx for the 2017–18 WNBL season. On 28 September 2017, just a week out from the start of the WNBL season, Farnworth was ruled out for up to 12 weeks with a broken wrist she suffered during pre-season play. On 25 November 2017, she was cleared to return three weeks ahead of the initial time frame. The Lynx finished on top of the ladder thanks to a 14-game winning streak, but a brutal travel schedule and string of injuries robbed them of the chance to taste ultimate success. She re-joined the Hawks in 2018, before re-signing with the Lynx on 14 June 2018.
