Heggem got his national team debut 25 February 1998 against France, scoring a goal. He was selected for the 1998 FIFA World Cup squad, but spent the entire tournament as a substitute. After the World Cup, Heggem transferred to Liverpool FC for £3.5m. His two initial seasons at Anfield were splendid, but the pacy right back/midfielder was unfortunately plagued by hamstring injuries. He played in the 2000 UEFA European Football Championship, but he got injured during the second match. During the 2000-01 season he appeared in only a few matches, and during the next two seasons he didn't appear in the lineup at all. Heggem left Liverpool FC when his contract ended in the summer of 2003, and shortly thereafter retired from football.
He is currently the owner and manager of a salmon fishing business at the river Orkla in Sør-Trøndelag. He is also an Official Patron of AFC Liverpool, an independent football club owned and run by Liverpool FC supporters.