The 25-year-old Dibaba out-kicked Kenya’s Helah Kiprop to win the gruelling event by just one second, crossing the finish line in two hours, 27 minutes and 35 seconds.
The long-striding Kiprop briefly threatened to take the gold medal when she loomed up on the outside of Dibaba with 50 metres left to run but couldn’t get past the pint-sized Ethiopian.
Kiprop faded slightly and had to settle for the silver medal, while the bronze went to the reigning Asian champion Eunice Kirwa, who was born in Kenya but now competes for Bahrain.
Ethiopia has a long and proud tradition in marathon running but Dibaba was the first Ethiopian female to win the lung-sapping event at the world championships.
“I’m so happy to get the first medal for my country,” she said through a translator.
“Just after 40km, I tried to test them. I came out in front because I wanted to control. Then we came into the stadium, I just tried my best.
“I take off and I win the marathon.”
Dibaba went into the race as the favourite after recording the fastest time in the world this year but was unable to shake off her mostly East African challengers on a overcast morning in the Chinese capital where conditions were less brutal than usual.
There were still a dozen runners in the leading pack at the 30 kilometres mark but as the pace picked up, they slowly began to drop off.
By the 35km mark, just six remained in the leading bunch, then five as they passed 40km.
Kenya’s Edna Kiplagat, who won the last two world championships marathons, dropped from the leading group about two kilometres from the finish and settled for fifth.
But there were still four women in contention when they reached the Bird’s Nest stadium. Kenya’s Jemima Sumgong lost touch in the entry tunnel and missed out on the podium despite finishing just seven seconds behind the winner.
Dibaba dashed clear as they reached the edge of the track. Kirwa tried to go with her but had no energy left and settled for the bronze.
“I had pain in my leg, so I decided to stay behind (the leaders) as the pace continued pushing, pushing,” she said.
“But at 35km, I see it’s better to push the pace because I was looking towards the finish line.”
Kiprop was the last to challenge Dibaba and although she came up short, she was pleased just to get on the podium, fearing she might be the unlucky one when the four leaders entered the stadium tunnel.
“Everyone was very strong, I was thinking that maybe I would be number four but at the end I saw it was possible for me to go and so I tried,” she said.
“I feel very excited because I didn’t expect (to win a medal). It was my first time to be at the world championships and the first time I represented my country.”
(Writing by Julian Linden in Singapore; Editing by John O’Brien/Sudipto Ganguly)