Having played his youth football for the
Birkirkara nursery, Montebello joined
Livorno's youth sector in 2011. He had some success with the Italian youth side, before returning to Malta and signing with
Valletta on a five-year contract. Montebello was sent out on loan to
Żebbuġ Rangers for the second half of the
2014–15 season in a bid to help them avoid relegation. In search of first team football, he joined
Tarxien Rainbows in summer 2015 on loan, scoring 12 goals in 31 matches in the
Maltese Premier League. He was again sent out on loan for the
2016–17 season, this time to woodenspoonists
Pembroke Athleta. This was short-lived however, as he was called back to Valletta for the second half of the season, after he injured his shoulder in October. He underwent surgery which turned out to be successful, however he still needed 7 to 8 weeks of recovery. In 2017, Montebello returned to his childhood club Birkirkara on a permanent deal. In January 2018, Montebello was banned for match-fixing for one year. After the suspension, he returned to play for Birkirkara again. In 2022, Montebello joined Ħamrun Spartans, where he would win the
Maltese Premier League in the 2022/23 season and would also win the subsequent
Maltese Super Cup. On the 18th of March 2025 Luke mutually parted ways with the club after an altercation with fans post Hamrun Spartan's 1-0 defeat to Sliema. On the 14th of April 2025 it was announced that Luke would be returning to a club in the summer, where he had spent some time as a junior, in the shape of Valletta F.C., who themselves had just come off a season, which saw an instant return to the Maltese Premier league, after a one-year absence. ==International career==