The Wales international, 23, topped the poll of journalists with a narrow victory over Manchester United forward Robin van Persie, who was last year's recipient when at Arsenal.
Bale's 24 goals in all competitions helped take Andre Villas-Boas' men into the quarter-finals of the Europa League and kept them in the race to secure a return to the Champions League via a top-four finish in the Barclays Premier League.
The Spurs midfielder will receive the prestigious FWA accolade, which has been running since 1948, at a gala dinner at the Lancaster London Hotel on May 9.
Chelsea's Juan Mata was third in the journalists' poll, with Bale taking first place with 53 per cent of the votes ahead of Van Persie.
There were also a wide range of votes for the likes of Everton defender Leighton Baines, Pablo Zabaleta of Manchester City, Swansea forward Michu, Manchester United midfielder Michael Carrick and Southampton frontman Rickie Lambert.
Bale becomes Spurs' first winner of the FWA award since David Ginola in 1999, and the first Wales international to be selected for English football's oldest individual trophy since Everton's Neville Southall in 1985.
The Tottenham midfielder said: "It is a huge honour to receive the Footballer of the Year award from the Football Writers' Association.
"It means a lot to win this award when you consider the number of players that have been outstanding for their clubs in the Barclays Premier League this season.
"I have been very fortunate to be playing in such a fantastic team and I owe a lot to my team-mates and, obviously, the manager who has shown such faith in me.
"This award has been won in the past by some of the greatest names in football and I consider it a privilege that the FWA has selected me to be named alongside them."
Chairman of the FWA Andy Dunn, chief sports writer for the Sunday Mirror, said: "In a contest for votes that took so many late twists and turns, Gareth's penchant for the spectacular captured the imagination.
"He is a player who is rising inexorably towards the rarefied levels of world stars such as Lionel Messi and Cristiano Ronaldo.
"Twice the PFA Player of the Year and now, two months before his 24th birthday, the FWA Footballer of the Year.
"Let's all hope he lights up the Barclays Premier League for many seasons to come."