The Exiles' promotion to the top flight was confirmed by an appeal hearing on Friday and they have been presented with a daunting opening fixture against the Tigers.
Oxford's Kassam Stadium - Welsh's home ground for the season - will host the game and a week later they face champions Harlequins at Twickenham Stoop.
Director of rugby Lyn Jones said: "It doesn't get much tougher than Leicester for our first game.
"They've been the most successful club in English rugby over the last 10 years and would give us a tough game with a second team.
"We're not dull, we know we must win five or six games to be here next season."
Harlequins open the defence of their first Premiership title against Wasps in the traditional double-header at Twickenham.
Round 1 fixtures
August 31 (or September 1 or 2):
Exeter Chiefs v Sale Sharks
Gloucester Rugby v Northampton Saints
Worcester Warriors v Bath Rugby
London Wasps v Harlequins, 2pm, live on ESPN
Saracens v London Irish, 4.30pm, live on ESPN
London Welsh v Leicester Tigers, 2pm, live on Sky Sports
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