Surprisingly, on the final lap it was world record holder Jebet who began to fall away first, and with Chepkoech falling behind at the water jump, it was here when Coburn made the decisive move.
Dafne Schippers of the Netherlands won in 22.05, followed by Ivory Coast's Marie-Josee Ta Lou in 22.08.
Coburn, whose bronze a year ago was the first medal of any color at the Olympics for an American woman in the event, credited an increased emphasis on having support and medical staff on hand at the biggest events, along with training differences.
She then turned round and successfully tried again before joining the rest of the pack and gradually eating into a gap that she herself had created.
These were the fourth and fifth medals for the US distance runners at the championships in London, including a bronze from Amy Cragg in the marathon, a bronze from Evan Jager in the men's steeplechase and a silver from Jenny Simpson in the 1,500.
When it came to crunch time, however, the Kenyan-born athlete slowed and was dropped by the leaders.
"I never expected to win in that time but I kept pressing".
Coburn and Frerichs raced near the front the entire way. "It is pretty awesome to get a championship record", she added.
American Kimberlyn Duncan finished just behind Stevens in sixth.
The 200m was unable to provide the drama of the preceding 3,000m steeplechase but still proved to be an absorbing battle.
Going into the closing weekend, the United States has eight gold medals.
Miller-Uibo was well on course to add the world title to the Olympic crown she earned at Rio 2016 before an extraordinary breakdown just 20m from the line, where she stumbled after losing concentration, dashed her hopes of victory. She ran an fantastic race to get the championship record.
The two Americans outran two Kenyans to the finish line Friday and ended up 1-2 in the steeplechase at world championships for the latest improbable - in this case, impossible? - triumphs for a stable of USA long-distance runners who keep getting stronger. Furthermore, Courtney Frerichs caused arguably an even bigger surprise to take the silver medal in a massive new personal best of 9:03.77, with defending champion Jepkemoi forced to settle for bronze. Kenya is second with three.