The 29-year-old, who played for Keighley Cougars and Wales, died from a cardiac arrest triggered by hereditary heart disease.
He collapsed on the pitch during a match at London Skolars on 3 May and efforts to resuscitate him failed.
His widow, Lizzie, has asked people to wear rugby league shirts for the service at St Mary's Church, Halifax.
Mrs Jones said she wanted the service, which began at noon, to be a celebration of the player's life.
BBC Look North's Heidi Tomlinson said hundreds of fans had gathered outside the church to watch the service on big screens.
A fundraising campaign set up by the RFL Benevolent Fund to support the couple's five-month-old twins has so far raised Â£150,000.
More than 2,000 people are attending the funeral of rugby league player Danny Jones.