Broady belied his 142nd ranking against a player who has reached three of the last five Grand Slam finals but had struggled at Wimbledon in his three previous appearances.
Broady made the running to take the first set and though Ruud regrouped to take the next two, it never felt as if he was taking control and the Briton was the dominant force in the fourth to take it to a decider.
Ruud, who said he had spent the three weeks since reaching the French Open relaxing well away from tennis, looked like he had mentally packed his bags again in the fifth as Broady ripped through it, barely dropping a point, to seal a memorable win.