In March 2002, Farrell was selected for New South Wales to play in the Under-17 interstate championships. She scored 26 runs at a batting average of 26.00 and took six wickets at a bowling average of 16.66. New South Wales won every match up until the final, where they collapsed for 60 to lose to Queensland. In January 2003, Farrell was selected for the Under-19 team and played in five matches. Her best performance was to score 49 and take 4/14 in a 123-run win over Tasmania. She took only one more wicket to end with five at 19.00 and scored 103 runs at 25.75. Farrell returned the following year and took 4/1 from three overs in the first match as New South Wales defeated Tasmania by ten wickets after dismissing them for 24. She then took 4/19 against Western Australia and ended with 11 wickets at 9.54 and scored 62 runs at 31.00 in two matches.

Farrell was selected for Australia’s team for the inaugural Women’s World Twenty20 held in England in 2009. The Australians hosted New Zealand for a three-match series in tropical Darwin at the beginning of June before the World Cup, and Farrell showed good form taking five wickets at 9.80 at an economy rate of only 4.45, with a best of 3/13 from four overs in the first match. However, she could not maintain the form. She took 1/29 from four overs in the team’s only warm-up on English soil, against the hosts, and was retained for all the matches, despite going wicketless in each of the three group matches and conceding 84 runs at an economy rate of 9.33. However, she was effective with the bat, scoring 13, 31 and 12, all unbeaten, against New Zealand, West Indies and South Africa respectively, the second innings coming when she was promoted up the order in an eight-wicket win. Australia lost to New Zealand but won the last two matches to reach the semi-finals. There she scored one not out before England overhauled Australia’s score of 5/163 to reach the final, which they won. Farrell was again ineffective, taking 1/32 from four overs. She ended the tournament with one wicket at 116.00 at an economy rate of 8.92.

In the 2010 Rose Bowl series, Farrell played in each of the five ODIs during the Australian leg of the competition. She took one wicket in each of the matches and made ducks in both of her innings. She ended the ODIs with five wickets at 21.60 and an economy rate of 3.25 as Australia won all five matches. The ODIs were followed by five T20 internationals, three at Bellerive Oval in Hobart and the last two in New Zealand. Farrell played in all but the fourth T20 game, taking five wickets at 17.80 and an economy rate of 6.35 and she batted twice, scoring two runs at 2.00. New Zealand won all five T20s and Farrell was left out of the three ODIs on New Zealand soil.

In June 2015, she was named as one of Australia’s touring party for the 2015 Women’s Ashes in England.