Robert Hagg was born on February 8, 1995 in Uppsala, Sweden. A standout for Modo in his homeland, Hagg was selected in the second round of the 2013 NHL Entry Draft by the Philadelphia Flyers. Hagg made his North American debut during the late stages of the 2013-14 season, suiting up for the Flyers’ AHL affiliate.
Hagg would spend three full seasons in the American League before getting his first glimpse of life in the NHL. On April 9 he made his Flyers debut during the club’s final game of the 2016-17 season in a 4-3 loss to the Carolina Hurricanes. He cracked the Flyers lineup the following season. In 70 games with Philadelphia the defenceman recorded three goals and six assists for nine points.