However, new accounts filed by the US Open winner show that McDowell’s Boyport Services Ltd recorded a $1.19m reduction in accumulated profits last year from $13.2m to $12m.
The drop in profits follows a stellar 2013 enjoyed by the firm when profits jumped by $3m.
During 2014, the cash pile at McDowell’s firm reduced from $5.72m to $4.18m while the value of investments at the firm jumped by more than $600,000 to $6.879m.
Last year was the final year in which McDowell’s career off the golf course was guided by the Dublin sports agency, Horizon Sports Management.
In August of last year, McDowell, also known as G-Mac, announced the parting of the ways with Horizon, confirming he was to manage his own commercial interests from the start of 2015.
He said at the time: “I am at a stage in my life where it feels right to move on to the next phase of my career - both in golf and business.”
When McDowell joined Horizon in November 2007, he was ranked outside the top 100 players in the world and during his time with Horizon he became a major champion, played in a number of Ryder Cups and won multiple tournaments around the world.
GMac in Germany and on the range for a late practise session at the @Porsche European Open. pic.twitter.com/REhEtCXXlj— G-Mac Apparel (@GMac_Apparel) September 21, 2015
At the end of last year, McDowell’s world ranking was 15.
However, he has since slipped to 67, with his ranking not helped by missing the cut in the US PGA and US Open this year and poor scores in the Open and the Masters.
The wealth of G-Mac’s firm has increased dramatically in recent years and away from his commercial and golf activities, the 36 year old operates The G-Mac Foundation whose mission is to support children’s medical research in Northern Ireland, the Republic of Ireland and the US.
In 2013, McDowell extended his business interests when he opened Nona Blue Tavern that houses a sports bar and a restaurant in Orlando where he has lived for the past 10 years.
McDowell’s success on the golf course has won him a slew of sponsors that includes credit card firm MasterCard; shoe and clothing firm Ecco; consultancy firm Teneo; financial services firm RBC; and golf ball and equipment-maker Srixon.
McDowell turned pro in 2002 and established Boyport Services that same year to manage his commercial success.