Giving the film four-out-of-four stars, Roger Ebert acknowledged that it was one of the "riskiest gambles a filmmaker has taken in a long time," but added "(here is the genius of the movie) there is nothing cheap or unworthy about the approach," and ultimately concluded that it was a "magnificent film, full and tender and funny and charming." Peter Travers of People magazine said that "Hulce and Abraham share a dual triumph in a film that stands as a provocative and prodigious achievement." Stanley Kauffmann of The New Republic put it on his list of films worth seeing. In one negative review, Todd McCarthy of Variety said that despite "great material and themes to work with, and such top talent involved," the "stature and power the work possessed onstage have been noticeably diminished" in the film adaptation.
In 1985, the film was nominated for eleven Academy Awards, including the double nomination for Best Actor with Hulce and Abraham each being nominated for their portrayals of Mozart and Salieri, respectively. The film won eight Oscars, including Best Picture, Best Actor (Abraham), Best Director (Forman), Costume Design (Theodor Pištěk), Adapted Screenplay (Shaffer), Art Direction (Karel Černý, Patrizia von Brandenstein), Best Makeup, and Best Sound. The film was nominated for, but did not win Oscars for Best Cinematography and Best Editing. Amadeus, The English Patient, The Hurt Locker, The Artist, and Birdman are the only Best Picture winners never to enter the weekend box office top 5 after rankings began being recorded in 1982. Amadeus peaked at #6 during its 8th weekend in theaters. Saul Zaentz produced both Amadeus and The English Patient.
The film was nominated for six Golden Globe Awards (Hulce and Abraham were nominated together) and won four, including awards to Forman, Abraham, Shaffer, and Golden Globe Award for Best Picture – Drama. Jeffrey Jones was nominated for Golden Globe for Best Supporting Actor – Motion Picture Drama. Forman also received the Directors Guild of America Award for his work.
At the end of the Oscar ceremony, Laurence Olivier came on stage to present the Oscar for Best Picture. As Olivier thanked the Academy for inviting him, he was already opening the envelope. Instead of announcing the nominees, he simply read, "The winner for this is Amadeus." An AMPAS official quickly went onstage to confirm the winner and signaled that all was well, before Olivier then presented the award to producer Saul Zaentz. Olivier (in his 78th year) had been ill for many years, and it was because of mild dementia that he forgot to read the nominees. Zaentz then thanked Olivier, saying it was an honour to receive the award from him, before mentioning the other nominees in his acceptance speech: The Killing Fields, A Passage to India, Places in the Heart and A Soldier's Story. Maurice Jarre won the Oscar for Best Original Music Score for his scoring of A Passage to India. In his acceptance speech for the award, Jarre remarked "I was lucky Mozart was not eligible this year".