Heigl, who was honoured as best supporting actress in a drama last year for the ABC series, declined to put her name in consideration for a bid, a spokeswoman for the actress said on Wednesday.
"I did not feel that I was given the material this season to warrant an Emmy nomination and in an effort to maintain the integrity of the academy organisation" decided against competing, Heigl said in a written statement from her publicist, Melissa Kates.
"In addition, I did not want to potentially take away an opportunity from an actress who was given such materials," added Heigl. She plays Dr Izzie Stevens on Grey's Anatomy, which slipped in the ratings this past season but remained a top 10 show.
An after-hours message left with a publicist for Grey's Anatomy creator and executive producer Shonda Rhimes was not immediately returned on Wednesday night.
Heigl, who shot to box-office success last summer with the comedy Knocked Up, has established herself as one of Hollywood's rare voices of candour.
In a Vanity Fair magazine interview published in January, she called the hit film "a little sexist" and said that it painted women as "shrews, as humourless and uptight," while the male characters were lovable and goofy.
Heigl also was outspoken when "Grey's" castmates Isaiah Washington and T R Knight clashed last year over Washington's alleged use of a homophobic slur.
"I'm going to be really honest right now, he needs to just not speak in public. Period," Heigl said at one point of Washington, who ended up being booted from the medical drama.
Nominations for the 60th Primetime Emmy Awards will be announced on July 17. The ceremony is September 21.
