Sussex Police launched an appeal after the 22-year-old died in an incident on Sunday, July 3.
Police said the collision happened on the B2112 New Road, between Ditchling and Clayton, shortly after 6am.
A police spokesperson said: “Jack Brandon, 22, from Hassocks was struck by a vehicle which failed to stop at the scene.
“His next-of-kin have been informed and are receiving support from specially-trained officers.”
Jack’s family told ITV that the young man was walking home from a wedding in the early hours of Sunday morning.
They said he had called his partner to let her know he would be home in ten minutes but did not arrive.
The parents of Jack’s girlfriend Sophie said on ITV that Jack was looking forward to becoming the father of a baby girl in October.
Police are urging anyone who saw what happened, or captured the incident on dash cam, to email [email protected], quoting Operation Kempston.
Police said officers would like to hear from anyone who sees a white van, possibly on a 2015 plate, which has damage to its headlight and is missing its onside wing mirror.
Oliver Dommett, who owns Pro-Finish Plastering Services in Worthing where Jack worked, set up a GoFundMe page to support Jack’s partner and daughter, which has now raised more than £15,000.
Writing on the GoFundMe page Oliver said: “Jack was an amazing person, a real character with an unmatched sense of humour.
“Jack was only in his early 20s but you wouldn’t find a harder worker with a heart of gold who would do anything for anyone.
“What makes the loss even more tragic is that Jack was on the brink of having his own young family with his baby girl due in October.
“I am asking for donations to help support and set Jack’s new family up and allow his partner Sophie to grieve at this time without the worry of the financial woes of becoming a new parent.”
People can support the family by donating to the GoFundMe campaign at www.gofundme.com/f/help-support-jacks-partner-and-daughter.