He was recruited by St Kilda with the 11th pick in the 1998 National Draft and made his senior debut in round five of the 1999 season.

Hayes was a first-choice player for St Kilda for virtually his whole career, other than in two seasons (2006 and 2011) where he would require knee reconstructions.

[1] Hayes was born in Sydney, New South Wales to mother Elizabeth and father Chris one of two boys (and two girls).

[2] Chris was an Australian rules player from Melbourne whose grandfather Vin Maguire, Lenny's great-grandfather, played for the Geelong Football Club.

He started well and improved throughout the year, earning an AFL Rising Star nomination in the final round of the season (R22).

With St Kilda's current policy being that of one to rotate the captaincy to a different player each season, Hayes would be named captain ahead of 2004.

Additionally, others included in the leadership group were Aaron Hamill, Fraser Gehrig, Nick Dal Santo and Robert Harvey.

Hayes played in 19 of the 22 matches in the 2009 home and away rounds in which St Kilda qualified in first position for the finals series, winning the club's third minor premiership.

Hayes played all games in 2012 and won his third Trevor Barker Medal as St Kilda's best & fairest player for the season.