Arnot started her career at Edinburgh City and later Hutchison Vale before she joined Hibernian in January 2012.[3] Arnot was part of the side that won consecutive Scottish domestic cup doubles in 2016 and 2017, and also finished as league runners-up on four occasions between 2013 and 2017.
In 2017, Arnot suffered a cruciate ligament injury, ruling her out for 14 months; on her return, she scored five goals for Hibernian in a 9–0 win against Celtic in the 2018 SWPL Cup final, retaining the title for the third straight year.[4]
Manchester United
On 27 June 2018, it was announced that Arnot and teammate Kirsty Smith were leaving Hibernian.[5] Both players joined the newly formed Manchester United for the 2018–19 season.[6] Arnot became the women's team's first ever goalscorer, scoring the only goal in the side's first competitive match, a 1–0 win against Liverpool in the FA Women's League Cup on 19 August.[7] A month later, she scored her first league goal of the campaign in a 3–0 home win against Sheffield United.[8] On 18 November 2018, Arnot scored her first United brace in a 0–5 win away to Crystal Palace.[9]
Arnot scored her first goal of the 2019–20 season in an 11–1 League Cup home win against Leicester City on 21 November 2019.[10] She left following the expiration of her contract at the end of her second season.[11]
Rangers
On 31 July 2020, Arnot returned to Scotland to sign with Rangers.[12] She scored 16 goals in 21 appearances as she won the 2020–21 golden boot.[13] During the 2021–22 season, Arnot contributed 25 goals and 23 assists in 31 appearances as Rangers won the Scottish Women's Premier League for the first time,[14] confirming the title in a 0–0 draw at home to Glasgow City. Arnot made her 50th appearance for Rangers in a 4–0 victory over Aberdeen at Ibrox Stadium, scoring the fourth goal. On 27 April 2022, Arnot was nominated for the PFA Women's Player of the Year award and was named in the PFA Scotland Team of the Year. On 28 May 2022, she signed a two-year contract extension.[citation needed]
In the inaugural match of the Women's Glasgow Cup, Rangers played Celtic on 24 July 2022 at Excelsior Stadium in Airdrie; Rangers lifted the trophy in a 2–1 victory, and Arnot's corner was turned into goal by Celtic captain Kelly Clark for the second goal.[15] On 8 November 2022, Rangers beat Hibernian 2–0 in the 2022–23 Scottish Women's Premier League Cup final at Tynecastle Park. Arnot scored a spectacular opening goal, was named player of the match[16] and later won "goal of the season".
On 4 February 2024, Arnot made her 100th appearance for Rangers in a 9–0 victory over Dundee United in Scottish Cup round of 16. Rangers retained the SWPL Cup in a 4–1 victory over Partick Thistle in the final at Tynecastle Park in March 2024. Two months later they narrowly missed out on the SWPL title on the last matchday (as they had also done in the previous season) but then won the 2023–24 Scottish Women's Cup with a 2–0 win against Hearts at Hampden Park, Arnot sealing club's first-ever Scottish Cup triumph with the second goal in the 86th minute.[17]
Arnot is the all-time leading goalscorer for Rangers Women.[citation needed]