In 2001–02 Simmons blossomed into a first team regular. He scored his first senior goal against Rangers in September to earn Hearts a 2–2 draw and netted a further 4 times during a season in which he also earned Scotland U21 recognition.
Simmons became a first-team regular for Hearts in the 2001-02 season. He scored his senior debut against Rangers in September, securing a 2–2 draw for Hearts and netting four more times that season, which also earned him Scotland U21 recognition.