He played his first game wearing number 28 for St Kilda in round 2 of the 2002 AFL season against the Collingwood Football Club.

[citation needed] Consolidating himself in the senior team, he went on to play 22 games for the season, leading the club in inside-50s, running bounces, and was top-five in tackles and hard-ball gets.

Although 2007 was the first since 2003 that St Kilda had missed out on playing in the finals series, it was the season that saw Montagna become a top-tier AFL footballer.

[citation needed] He played an accountable and hard-running role through St Kilda's midfield, averaging 24 disposals and 3 tackles per game and kicking 10 goals for the year.

He played in 21 of 22 matches in the 2009 home-and-away season, where St Kilda won the minor premiership and qualified in first position for the finals series.

[citation needed] Considered a Brownlow Medal contender in 2009, Montagna took out a third-place finish in a tight St Kilda best-and-fairest count as well as earning an All-Australian position for the first time.

Montagna played 26 games in 2010, including the infamous draw and replay grand finals, averaging 28.6 possessions.

[7] He finished second in St Kilda's best-and-fairest award (Trevor Barker Medal), was selected in the AFL's All-Australian team for the second year in a row, finished in the top 10 in the Brownlow medal, and capped off the year by representing Australia in the International Rules series for the second time.

Leigh Montagna played his 150th game against Richmond in a draw in Round 2 of the 2011 AFL season at the Melbourne Cricket Ground.

[citation needed] He played 102 out of 110 games in that period, averaging 26.4 disposals and finishing fourth in the club best and fairest as well as representing Australia on two more occasions.