The Australian was diagnosed with testicular cancer in 2011, after a random drugs test at the Under-17 World Cup had uncovered a tumour.
After undergoing surgery and chemotherapy, Tombides was able to return to action and made his senior West Ham debut in a League Cup tie with Wigan Athletic at Upton Park in September 2012.
He also represented his country this January in the AFC Under-22 Championship in Oman.
However, his illness then returned and Tombides passed away on Friday with his family by his side.
A statement from West Ham hailed the courage and bravery of a player who had been tipped to enjoy a successful career in professional football.
He remained a regular visitor to Chadwell Heath throughout his treatment and his positive attitude and professional approach to his football and training always impressed and boosted his team-mates and coaches alike, read the statement.
Dylans amazing resilience and positivity saw him through months of surgery and chemotherapy, while his outstanding talent saw him make his first-team debut in a League Cup tie with Wigan Athletic at the Boleyn Ground in September 2012.
Away from the pitch, Dylan did a huge amount of work to raise awareness of male cancer, supporting the One for the Boys campaign at a number of high-profile events alongside the likes of Hollywood star Samuel L. Jackson, snooker star Jimmy White and fellow Australian Peter Andre.
Dylan was respected by everyone who knew him for his intelligent views on the game and his larger than life character. He was a loving son, amazing brother and well-respected member of the West Ham squad.
He will be hugely missed by everyone who had the honour of knowing him.
The thoughts of everyone associated with the club are with his parents Tracylee and Jim, brother Taylor, his family and friends at this sad time. The club request that their privacy is now respected and they are allowed to grieve their much loved son and brother in peace.
Tombides younger brother, Taylor, is also on the books at West Ham and said on Twitter: R.I.P. Dylan my beloved brother you will be missed but never forgotten you was a massive inspiration to everyone.
A minutes applause will take place to mark Tombides passing prior to West Hams Premier League game against Crystal Palace on Saturday.
David Gallop, the Football Federation of Australias CEO, also paid tribute to Tombides in a statement.
On behalf of the Australian football community, we offer our deepest condolences to Dylans family, team mates and friends during this extremely sad time, said Gallop.
The Tombides family has lost a fine young man and Australian football has lost one of its most promising football players.
He will be remembered for the courage he showed in his personal battle as much as the prodigious talent he displayed on the football field.