O'Hare was born and brought up in West Linton and attended Peebles High School. He subsequently completed a degree in sports science at the University of Tulsa in the United States, together with his sister Olivia.[5] His younger brother Dominic competed in middle-distance running in Scotland.[2] O'Hare is married and is a fan of Celtic FC.[6]
O'Hare won the Mile at the NCAA Men's Division I Indoor Track and Field Championships 2012 with a time of 4:01.66[8]
O'Hare was selected for the 1500 m at the 2013 IAAF World Athletics Championships in Moscow after he became the first Scottish athlete in over 35 years to top the UK rankings at the distance. At the Worlds he qualified for the final, where he finished 12th, becoming the first British athlete to qualify for the 1500 m final for six years.[6]
O'Hare was selected to compete in the 1500 metres event at the 2016 Olympic Games.[10] He progressed from the heats, but having come eleventh in his semi-final he didn't reach the final.