Thousands of West Ham supporters turned out on the streets of Newham to celebrate their team's promotion. An open-top bus took the team from Newham Town Hall in East Ham at 1830 BST and along Barking Road, with the journey ending at the Boleyn Ground.
"We've had two years of darkness in the Championship but now we are going into the light of the Premiership," said Hammers' manager Alan Pardew.
Bobby Zamora's goal earned a play-off final win over Preston on Monday.
"It was a fantastic day in Cardiff and congratulations to the Hammers," said Mayor of Newham Sir Robin Wales.
Zamora's match-winning goal at the Millennium Stadium sent the thousands who travelled to Cardiff into delirium after a two-year absence from English football's top-flight.
Alan Pardew's side finished sixth in the Championship and Pardew is now expected to be given around �20m to held keep the Hammers in the Premiership.
Pardew admitted he would have to act quickly to sign the players the club need to compete with the country's top clubs next season.
"The window for us to sign players is now. The Premiership season finished a couple of weeks ago and clubs up there have already started manoeuvring, so we have to get in the ballpark quickly," said Pardew.
Managing director Paul Aldridge added: "We will give it a real go. Things have not been easy over the last couple of years and we have to be sensible but we want to stay in the Premiership.
"We are delighted to be back up there and will do everything we can to give ourselves a good chance of staying put."