Awards president Tom Sherak said that he looked forward to "renowned filmmaker" Grazer joining Don Mischer to helm the 84th Academy Awards for the first time ever.
Sherak said: "Brian Grazer is a renowned filmmaker who over the past 25 years has produced a diverse and extraordinary body of work. He will certainly bring his tremendous talent, creativity and relationships to the Oscars."
Mischer added: "I am thrilled to welcome Brian Grazer as my partner and that we will be collaborating to produce an outstanding show."
Grazer, who was already linked to the project earlier today, said: "It's very gratifying to be part of a show that honours excellence in the medium to which I have devoted so much of my career. Don is a legend, and I am excited to work with him."
Academy CEO Dawn Hudson said that she was "delighted" at the new appointment and said that she hopes Grazer can help make the 2012 Oscars show the "movie event of the year".
Grazer won a 'Best Picture' Academy Award in 2001 for Russell Crowe movie A Beautiful Mind. He was also nominated for Apollo 13 and Frost/Nixon and has worked on movies such as The Nutty Professor and Liar Liar.
Murphy was originally expected to host the event but quit earlier today when Ratner handed in his resignation after his recent 'gay slur' controversy.
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