Los Angeles, California (CNN) -- The final score: David 6, Goliath 3.

"The Hurt Locker" earned six Oscars at the 82nd annual Academy Awards Sunday night, taking home the biggest prize -- best picture -- as well as honors for its director, original screenplay, sound editing, sound mixing and film editing.

The small-budget movie, one of the lowest-grossing films to be nominated in the post-"Star Wars" blockbuster era, defeated its primary competition, James Cameron's "Avatar," the big-budget, highest-grossing film of all time. The groundbreaking "Avatar," with its dazzling effects and creative presentation, won three Oscars, for cinematography, visual effects and art direction.

Both films led the pack with nine nominations each.

Complete list of winners

"The Hurt Locker," a film about a bomb disposal unit in the early part of the Iraq War, developed its momentum slowly, winning notice at festivals in the latter part of 2008 before earning a national release in the summer of 2009. Despite fading quickly at the box office -- to date, it's earned just $21 million worldwide, versus more than $2.6 billion for "Avatar" -- it was remembered by critics and peers at the end of the year, winning several awards.

"Locker" director Kathryn Bigelow made history by becoming the first woman to win the directing prize. Presenter Barbra Streisand opened the envelope with, "Well, the time has come!" as a loud standing ovation and lots of shrieks greeted Bigelow's arrival on the stage.

"There's no other way to describe it -- it's the moment of a lifetime," she said, accepting her directing prize. She dedicated her honor "to the women and men in the military who risk their lives on a daily basis... may they come home safe."

Earlier, writer and producer Mark Boal, who based the script on his reporting from Iraq, paid tribute to director Bigelow, "all of the soldiers still over there and those who have died" and to his father, who passed away a month ago, he said in his acceptance speech.

The acting awards were divided between old favorites and rising newcomers.

Sandra Bullock won best actress for her performance as a forceful mother who brings a homeless teen into her well-off family in "The Blind Side."

Bullock started her speech with jokes, paying tribute to her "lover, Meryl Streep" -- a fellow nominee -- and asking, "Did I really earn this or did I just wear you all down?" But her voice cracked with emotion as she dedicated her award to "the moms that take care of the babies and the children, no matter where they come from," and then turned her attention to her own mother, whom Bullock described as firm but supportive.

Jeff Bridges won the best actor Oscar for his performance as an alcohol-soaked country singer in "Crazy Heart."

"Thank you, Academy members!" he exulted, raising his Oscar high. "Thank you Mom and Dad for turning me on to such a groovy profession. ... They loved showbiz so much, and I feel like an extension of them. This is as much for them as it is for me."

Bridges' father was Lloyd Bridges, star of the TV show "Sea Hunt" and many movies, and his mother was actress Dorothy Bridges.

The nominated song from "Crazy Heart," "The Weary Kind," won best original song.

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Mo'Nique won the best supporting actress Oscar for her role as Mary Jones, an abusive mother in "Precious."

In a fierce and memorable acceptance speech, she thanked the Oscar voters "for showing that it can be about the performance and not the politics."

"I want to thank Miss Hattie McDaniel for enduring all that she did so I don't have to," Mo'Nique said.

McDaniel was the first African-American to win an Academy Award when she was given the best supporting actress Oscar for playing Mammy in the 1939 film "Gone with the Wind."

Mo'Nique said before the show that she was wearing a gardenia in her hair in tribute to McDaniel, because she wore one for her acceptance speech 70 years ago.

She also thanked Tyler Perry and Oprah Winfrey, who helped director Lee Daniels land a distribution deal for the movie.

"Because you touched it, the whole world saw it," Mo'Nique said.

Backstage, Mo'Nique was asked whether she still considered herself a stand-up comedian now that she is an Oscar-winning actress.

"I am a standup comedian who won an Oscar," she said.

The success of her role "was so not about my acting career," she said. "This role was about my life, to teach me not to judge."

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The story of a downtrodden inner-city teenager also pulled off a mild upset earlier, winning best adapted screenplay over perceived front-runner "Up in the Air."

"I don't know what to say," said visibly moved writer Geoffrey Fletcher, paying tribute to the filmmakers, his two brothers, his mother and father. "I thank everyone," said Fletcher, gasping emotionally.

Christoph Waltz won the first Oscar of the night, a best supporting actor award for "Inglourious Basterds."

"This is your welcoming embrace, and there's no way I can ever thank you enough," Waltz said. "But I can start right now, thank you."

"Up" won best animated feature, yet another victory for the Pixar studios, which has dominated the category since its introduction for the 2002 awards. Pixar has now won three straight animated feature Oscars and five of the nine overall. Michael Giacchino's music for the film won best score.

Best foreign language film went to "The Secret in Their Eyes," from Argentina. "The Cove" won best documentary feature.

Hosts Steve Martin and Alec Baldwin kept the ceremony moving until the big-award slowdown at the end. The two were lowered from the ceiling after an over-the-top opening number featuring a singing-and-dancing Neil Patrick Harris, and maintained a Bob Hope/Bing Crosby rhythm through much of the festivities, zinging one-liners at all and sundry.

And in a moving tribute, several stars of John Hughes movies -- including Molly Ringwald, Matthew Broderick, Jon Cryer, Judd Nelson, Ally Sheedy, Anthony Michael Hall and Macaulay Culkin -- came out to talk about the director of "The Breakfast Club" and "Ferris Bueller's Day Off," who died in 2009. Hughes' family, which was sitting in the audience, received an ovation.

CNN's Todd Leopold contributed to this story.