Juniors

As a junior, Mousley reached a career-high ITF Junior combined ranking of world No. 14, which is achieved on March 3, 2014. Partnering compatriot Jay Andrijic, he won the 2013 Australian Open boys' doubles tournament as a 17 year old. He successfully defended the title, winning the boys' doubles championship for the second consecutive year at the 2014 Australian Open, this time alongside partner Lucas Miedler of Austria.

2014

In August 2014, Mousley received a one-year ban, backdated to 30 May 2014, after testing positive for ecstasy in March. Mousley had admitted he had taken the drug at a party in March, and was originally given a two-year ban, but since the drug was not taken with the intent to enhance his performance, the ban was dropped to 12 months.^[3][4]

2017: Australian Open quarterfinal in doubles

At the 2017 Australian Open, Mousley and partner Alex Bolt were granted a wildcard entry into the men's doubles main draw. Unexpectedly, they won three consecutive matches to reach the quarterfinals of the Grand Slam tournament, before being defeated by Spanish duo Pablo Carreño Busta and Guillermo García López in three sets.

2019

While competing in M15 World Tennis Tour tournament in Hua Hin Thailand, he unfortunately injured his knee badly enough to have to withdraw from his singles semi-final match earlier in the day, and struggled to move freely from the start of his doubles finals match. He and partner Ajeet Rai were well-beaten by the top-seeded Ratiwatana twins in just 40 minutes.

Mousley has won 2 singles titles and 18 doubles titles on the ATP Challenger and ITF Futures Tours.

Singles: 8 (2–6)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Loss	0–1	Jun 2015	Turkey F24, Istanbul	Futures	Hard	Mārtiņš Podžus	1–6, 0–6
Loss	0–2	Aug 2015	Turkey F30, Erzurum	Futures	Hard	Alexander Igoshin	6–7(3–7), 6–4, 6–7(6–8)
Win	1–2	Apr 2016	Greece F3, Heraklion	Futures	Hard	Vladyslav Manafov	6–4, 6–3
Loss	1–3	Aug 2016	Egypt F18, Sharm El Sheikh	Futures	Hard	Nikola Milojević	6–3, 3–6, 3–6
Loss	1–4	Mar 2017	Australia F1, Mildura	Futures	Grass	Dayne Kelly	6–4, 4–6, 6–7(4–7)
Loss	1–5	Apr 2017	China F5, Luzhou	Futures	Hard	Fajing Sun	6–7(2–7), 2–6
Win	2–5	Oct 2017	Australia F5, Brisbane	Futures	Hard	Benjamin Mitchell	6–3, 4–6, 6–2
Loss	2–6	Feb 2018	Launceston, Australia	Challenger	Hard	Marc Polmans	2–6, 2–6

Doubles: 32 (18–14)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Loss	0–1	May 2013	Spain F13, Lleida	Futures	Clay	Jay Andrijic	Miguel Ángel López Jaén Jordi Marse-Vidri	5–7, 4–6
Win	1–1	May 2013	Spain F14, Valldoreix	Futures	Clay	Jay Andrijic	Miguel Ángel López Jaén Jordi Marse-Vidri	6–3, 6–4
Loss	1–2	Mar 2014	Australia F2, Port Pirie	Futures	Hard	Jordan Thompson	Gavin Van Peperzeel Maverick Bains	3–6, 3–6
Win	2–2	Apr 2014	Australia F4, Melbourne	Futures	Clay	Jordan Thompson	Adam Hubble Matt Reid	walkover
Loss	2–3	Jun 2015	Turkey F23, Bursa	Futures	Hard	Tuna Altuna	Julien Dubail Yannick Jankovits	2–6, 2–6
Win	3–3	Jun 2015	Turkey F24, Istanbul	Futures	Hard	Tuna Altuna	Fedor Chervyakov Aleksandre Metreveli	7–6(7–1), 7–6(7–2)
Win	4–3	Jun 2015	Turkey F25, Istanbul	Futures	Hard	Tuna Altuna	Temur Ismailov Markos Kalovelonis	6–4, 6–4
Loss	4–4	Jul 2015	Great Britain F6, Frinton	Futures	Grass	Evan Hoyt	Daniel Smethurst Marcus Willis	4–6, 4–6
Win	5–4	Aug 2015	Turkey F30, Erzurum	Futures	Hard	Tuna Altuna	Alexander Igoshin Daniel Glancy	7–5, 6–4
Loss	5–5	Nov 2015	Traralgon, Australia	Challenger	Hard	Omar Jasika	Dayne Kelly Marinko Matosevic	5–7, 2–6
Loss	5–6	Mar 2016	Australia F3, Mornington	Futures	Clay	Gavin Van Peperzeel	Greg Jones Andrew Whittington	3–6, 2–6
Loss	5–7	Mar 2016	Australia F4, Mornington	Futures	Clay	Gavin Van Peperzeel	Steven de Waard Marc Polmans	2–6, 3–6
Win	6–7	Apr 2016	Greece F4, Heraklion	Futures	Hard	Vladyslav Manafov	Edward Corrie Lloyd Glasspool	6–2, 6–3
Loss	6–8	Apr 2016	Greece F5, Heraklion	Futures	Hard	Vladyslav Manafov	Karol Drzewiecki Bruno Sant'Anna	6–7(3–7), 6–2, [7–10]
Win	7–8	May 2016	Croatia F5, Bol	Futures	Clay	Omar Jasika	Tobias Simon Tallon Griekspoor	7–5, 7–6(7–5)
Loss	7–9	Jul 2016	Germany F5, Kamen	Futures	Clay	Scott Puodziunas	Johannes Härteis Hannes Wagner	6–7(6–8), 6–2, [6–10]
Win	8–9	Jul 2016	Egypt F17, Sharm El Sheikh	Futures	Hard	Marek Jaloviec	Lorenzo Frigerio Andrea Vavassori	2–6, 6–3, [10–4]
Win	9–9	Aug 2016	Egypt F18, Sharm El Sheikh	Futures	Hard	Marek Jaloviec	Luca Pancaldi Andrea Vavassori	6–1, 6–2
Win	10–9	Aug 2016	Egypt F20, Sharm El Sheikh	Futures	Hard	Nathan Eshmade	Imran Aswat Alexander Merino	6–1, 6–0
Win	11–9	Oct 2016	Australia F6, Brisbane	Futures	Hard	Dayne Kelly	Harry Bourchier James Frawley	6–2, 6–3
Win	12–9	Feb 2017	Launceston, Australia	Challenger	Hard	Luke Saville	Alex Bolt Andrew Whittington	6–2, 6–1
Win	13–9	Mar 2017	Australia F3, Canberra	Futures	Clay	Marc Polmans	Steven de Waard Scott Puodziunas	6–4, 7–6(7–4)
Win	14–9	Jun 2017	Turkey F23, Istanbul	Futures	Clay	Mario Vilella Martínez	Hugo Dellien Federico Zeballos	6–3, 6–3
Loss	14–10	Jun 2017	Portugal F8, Lisbon	Futures	Hard	Sam Barry	Nuno Borges Francisco Cabral	1–6, 6–3, [5–10]
Loss	14–11	Sep 2017	Australia F4, Alice Springs	Futures	Hard	Darren Polkinghorne	Dane Propoggia Scott Puodziunas	4–6, 4–6
Win	15–11	Oct 2017	Australia F6, Toowoomba	Futures	Hard	Zhe Li	Nathan Pasha Darren Polkinghorne	6–4, 7–6(7–4)
Win	16–11	Oct 2017	Traralgon, Australia	Challenger	Hard	Alex Bolt	Evan King Nathan Pasha	6–4, 6–2
Win	17–11	Nov 2017	Canberra, Australia	Challenger	Hard	Alex Bolt	Luke Saville Andrew Whittington	6–3, 6–2
Win	18–11	Feb 2018	Launceston, Australia	Challenger	Hard	Alex Bolt	Sekou Bangoura Nathan Pasha	7–6(8–6), 6–0
Loss	18–12	Apr 2018	Leon, Mexico	Challenger	Hard	John-Patrick Smith	Gonzalo Escobar Manuel Sánchez	4–6, 4–6
Loss	18–13	Sep 2018	Zhangjiagang, China	Challenger	Hard	Akira Santillan	Mao-Xin Gong Ze Zhang	walkover
Loss	18–14	Aug 2019	M15 Hua Hin, Thailand	World Tennis Tour	Hard	Ajeet Rai	Sanchai Ratiwatana Sonchat Ratiwatana	2–6, 0–6

Doubles: 2 (2 titles)

Outcome	Year	Championship	Surface	Partner	Opponent	Score
Winner	2013	Australian Open	Hard	Jay Andrijic	Maximilian Marterer Lucas Miedler	6–3, 7–6(7–3)
Winner	2014	Australian Open	Hard	Lucas Miedler	Quentin Halys Johan Sébastien Tatlot	6–4, 6–3