Mooney began his rugby career with London Irish in 1992, making his debut as a prop against Bath aged 20 years old. He represented London Irish in both premiership and European competitions. Mooney played in the club's biggest premiership win, beating Harlequin F.C. 62–14 in April 1998. He was a member of the promotion winning team that took London Irish to the English Premiership in 1996, as well as the semi-final of the Pilkington Cup, under the leadership of Sir Clive Woodward. He moved on to play for Blackheath and Exeter Chiefs. From 1996 in the professional era, Mooney scored 14 tries and made over 100 appearances for his clubs. While at Exeter, he played for the English National Divisions and scored the winning try against the Springboks on their 2000 tour of the UK. During his career, Mooney represented Ireland XV, Ireland A, Ireland U21, Ireland Students, the Barbarians and won two Cambridge Blues representing Cambridge University in the winning 1994 and 1995 Varsity matches. He finished his rugby career at Bristol and Caerphilly where he retired with a chronic knee injury.
Business career
Mooney qualified as a solicitor of England & Wales in November 2000, having trained and worked at international law firm Kennedys and regional legal 500 law firm, Michelmores. In 2002, Mooney founded Blue Pencil, an international legal executive search and recruitment company, where he is currently the Managing Director. Blue Pencil is mentioned in Sidney Korshak's book "How to Land a Legal Job Overseas". In 2013, Mooney founded Club Fit For Business, a non-profit global sports business community. In November 2014, he was named by Arabian Business as 'Business Mentor of the Year' and was a finalist at the SME Stars of Business Awards in December 2014. Mooney currently serves as a non executive director to several companies in the SME sector as well as mentoring a number of retired professional athletes. In August 2015, Mooney was named as a finalist in the Gulf Capital SME Awards, as the “Business Leader of the Year”.
A lifetime member of Cambridge University Rugby Union Football Club, and a donor of the CURUFC's Red Lion Foundation, set up to support rugby players through their studies at the university, Mooney made a charitable donation to fund the Lion's Room in 2013. As an alumnus of Hughes Hall, Mooney supports Hughes Hall's Enterprise Scheme, which promotes entrepreneurship in young students at Cambridge University. Mooney also served as a committee member of the Oxford & Cambridge Society in the UAE, overseeing international relations with Oxford and Cambridge University alumni worldwide. Mooney is a keen supporter of animal conservation charities and in 2012 he organised a team of ten amateur runners to run the Dubai Marathon, to raise money for Tiger Awareness, a tiger conservation charity. Mooney also supports a number of local and international charities through Club Fit For Business, that have a focus on social inclusion for children through sport.