He left Hearts to play for Newcastle United in April 1988. Robertson failed to score in 14 Newcastle competitive first team games and returned to Hearts in December of that year, and remained there for the next decade. In 1998 Hearts won the Scottish Cup with Robertson an unused substitute, earning him his only senior medal as a player. In this second spell at Hearts he scored at a much less prolific rate compared to his first spell, with this time 106 goals in 310 league games. After an earlier loan spell with Dundee scoring once in 4 league games, he left Tynecastle that summer. He joined Livingston as a player-coach, scoring 14 goals in 41 league games.