Captain Phillips was educated at Marlborough College and at Sandhurst, following which he entered the Queen's Dragoon Guards in 1969. In 1972, he was a member of the British three-day event team at the Munich Olympics. They finished the event in gold medal position. It was through his equestrian activities that he met Princess Anne, and they were married on November 14, 1973 at Westminster Abbey. It is believed to have been her specific wish that, contrary to precedent, her husband did not receive a peerage on their marriage.
Two children were born to the couple: Peter (born 1977) and Zara (born 1981). However, rumours of a stormy relationship were rife, and their home life at Gatcombe Park was the subject of much unwanted media attention throughout their marriage. It was alleged in the press that the British royal family had nicknamed Captain Phillips "Fog".
Mark Phillips is the father of an illegitimate daughter named Felicity Tonkin (born c. 1985) who lives in New Zealand. The girl's mother is Heather Tonkin, an art teacher, and daughter of Dr. Shirley Tonkin, a renowned expert in Sudden Infant Death Syndrome . Heather Tonkin lodged the paternity suit with a court in New Zealand in 1991, and DNA testing later confirmed that Mark Phillips was indeed the father of her child .
Mark Phillips remains a leading figure in British equestrian circles.