Levin and Grace qualified for the year's second major after ensuring they will be in the top 60 when the latest rankings are issued on Monday.
Grace, a three-times winner on the European Tour this year, will make his US Open debut while Levin will play in the championship for a third time.
While Grace comfortably qualified after being ranked 54th last week, Levin squeezed in despite missing the cut at the St. Jude Classic in Memphis on Friday after points dropped off his world ranking ledger and he edged up from 61st to 60th to dislodge Ryo Ishikawa.
Japan's Ishikawa had already booked his place at the June 14-17 US Open by being ranked in the top 60 as of May 21.
The USGA have also added three alternates, Americans Justin Hicks, Kyle Thompson and Colt Knost, to complete the 156-strong field at San Francisco's Olympic Club.