The 20-year-old Australian died yesterday following a three-year battle with testicular cancer.
A minute's applause was held before today's match got underway to mark his passing, while Tombides's shirt was placed in the centre circle.
The club shared an image of some of the tributes that have been left at the ground on their Twitter feed shortly before kickoff.
PIC: Hammers fans have been leaving tributes to Dylan Tombides at the Boleyn Ground. pic.twitter.com/G3bHOH3VGp— West Ham United FC (@whufc_official) April 19, 2014