The 29-year-old German secured the prime starting position by persevering on his final lap in rapidly-drying conditions as Mercedes team-mate and home hero Briton Lewis Hamilton pulled into the pits, thinking like most observers that he was already safe on pole.
It was a sensational finish to an unpredictable session that saw both Ferrari and both Williams eliminated in the Q1 part of qualifying and which delivered surprises throughout.
For Rosberg, it was his fourth pole of the year, drawing him level with Hamilton, his first at Silverstone and the eighth of his career and gave him a great opportunity to enlarge his 29 points lead in the drivers' championship.
"We sat in the garage and eventually came to the conclusion that we might as well go out and have a look. Then it seemed like it was worth it because the last part of the lap was very dry. It was a great team effort."
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Hamilton had dominated until the final seconds when, thinking he was secure, he went to the pits while his rivals improved their times by more than three seconds in the final sector of the lap.
Hamilton wound up in sixth place ahead of Mexican Sergio Perez in the second Force India and Australian Daniel Ricciardo in the second Red Bull.
Asked why he pulled in, a bitterly disappointed Hamilton said: "I don't know, I don't have much of an answer... I just decided not to do the lap." He added that he did not believe it was dry enough for him to improve his time.