The midfielder with 20 goals to his name this term is only the fourth player behind Ryan Giggs (1991-92, 1992-93), Robbie Fowler (1994-95, 1995-96) and Wayne Rooney (2004-05, 2005-06) to win the prestigious award in successive seasons.
Dele, 21, held off the challenge of team-mate Harry Kane, Michael Keane (Burnley), Romelu Lukaku (Everton), Jordan Pickford (Sunderland) and Leroy Sane (City).
He said: "It's a huge honour to be voted the winner of the award again by my fellow players.
"To win it back to back is something I'm truly proud of and I'm grateful to my team-mates and everyone at the Club as I couldn't have won it without them.
"It's great to be recognised and to see the names that have won it in the past is amazing. I can't get carried away though and will focus on learning and improving to help the team."
Dele is the fifth Spur to win the PFA Young Player award. The first was Glenn Hoddle back in 1979-80 before our recent domination of the award - Kyle Walker, Gareth Bale, Harry Kane and now Dele have won it in five of the last six seasons.
PFA YOUNG PLAYER OF THE YEAR - SPURS WINNERS
1979-80 - Glenn Hoddle
2011-12 - Kyle Walker
2012-13 - Gareth Bale
2014-15 - Harry Kane
2015-16 - Dele Alli
2016-17 - Dele Alli