Dr Courtney is currently Associate Professor and National Heart Foundation Future Leader and previous National Health and Medical Research Council (NHMRC) Career Development Fellow (CDF) in Health Behavior science at the University of New South Wales (UNSW), National Drug and Alcohol Research Centre (NDARC). A/Prof Courtney's prior appointments were Cancer Institute NSW Early Career Fellow and Australian Rotary Health PhD Scholar (2008-2012) at the Priority Research Centre Health Behaviour, University of Newcastle.

A/Prof Courtney has authored or co-authored over 40 publications in the medical, public health and health behaviour literature. His published work includes research on smoking cessation, in particular tobacco smoking in low socio-economic status (SES) and disadvantaged populations. His research has a strong focus on the relationships between social disparities, including socio-economic inequalities and health behaviours and outcomes. 

A/Prof Courtney has attracted over $14 million in competitive research funding since 2015, in which over 90% of research support is from Category 1 funding agencies i.e. the most competitive health and medical research grants in Australia. A/Prof Courtney is currently Principal Investigator of three-large scale NHMRC-funded projects: i) a large-scale RCT (APP1162583/$1.7mill/4years) evaluating the cost-effectiveness of text messaging quit support versus Quitline for smoking cessation along low-SES smokers; ii) a clinical trial comparing the cost-effectiveness of vaporised nicotine products (VNPs) versus nicotine replacement therapy for low-SES smokers (APP1127390/$1.4mill/4years) and iii) RCT comparing the cost-effectiveness of VNPs vs varenicline for smoking cessation among low-SES smokers (APP2015146/$2.6mill/4 years). 

 As Chief Investigator B (CIB) A/Prof Courtney was responsible for the conceptualisation, design and successful completion of Australia's largest clinical trial in smoking cessation (n = 1452); a world-first head-to-head trial between cytisine and varenicline for smoking cessation that received funding from the NHMRC (APP1108318/$1.9mill/4years) published in the Journal of American Medical Association (JAMA). He is also CI on an NHMRC-funded project (APP1106451/$1.6mill/5years) examining the impacts of VNPs on youth smoking. In addition, A/Prof Courtney was also CI on other research projects including: NIHR/NHMRC (APP1095880/$913k/4years) collaborative grant funding to test the efficacy of electronic cigarettes for relapse prevention; and Department of Health-funded (H1516G012/$771k/2years) RCT of a smoking, nutrition, alcohol and physical activity (SNAP) to prevent  smoking relapse for Indigenous Australian prisoners.

A/Prof Courtney received the Dean’s Rising Star Award in 2013, in recognition of his achievements as an early career researcher, from the Dean of Medicine at the UNSW. Dr Courtney was the inaugural recipient of the UNSW, NDARC Margaret Hamilton Award for Research Excellence (December, 2015). This award is open to all Level A (Associate Lecturer) and Level B (Lecturer) researchers and the Award is determined by research support scheme (RSS) points (measured via research outputs including papers and grants). Recently he received the 2016 Global Forum on Nicotine Young Investigator Award in recognition of notable achievement in the field of nicotine science and/or policy and also UNSW, NDARC's Ian Webster Awards (2018-19 and 2022-23) for outstanding research achievement. This award is open to all Level C (Senior Lecturer) researchers and determined by RSS points. He was also recipient of the 2021-2022 UNSW, NDARC Wayne Hall Publication Award.