The world record holder and Olympic champion - unbeaten in more than two years - only sneaked into the final round of eight jumpers in last place before summoning a magical 15.08 metres on her final attempt to overtake Maryna Bekh-Romanchuk (28) of Ukraine.
Rojas, whose world record is a massive 15.74m, was eighth with just 14.33m and three fouls through five jumps, throwing her hand up in frustration with each failed attempt.
After flying past the 15m mark in the pit, she squeezed her eyes shut hopefully before the winning distance was posted.
"It was very difficult," Rojas said. "The fact that I won the competition with my last attempt makes it very special and memorable. This is my seventh World Championships gold in a row (outdoors and indoors) but this is the most special of all of them."
Bekh-Romanchuk, silver medallist in the long jump at the 2019 worlds, had to settle for another silver with 15.00.
"Maybe people saw my calm, focused and confident face, but believe me, nobody knows what I felt deep inside," said Bekh-Romanchuk, whose best jump was her opener.
"You cannot imagine how many people helped me to step on the podium tonight, especially during last month when I got a couple of injures. I think Yulimar Rojas also had a difficult season, but I was sure she could jump over 15 metres."
Leyanis Perez Hernandez (21) of Cuba won the bronze with 14.96.
"I knew if someone could change the result at the last minute, it would be Yulimar Rojas," Perez Hernandez said.
"It is my first medal at a World Championships and I am very proud, but today was not my day. I did not have my moment, which only means that I will continue to work hard and develop.
"I have some bitter feelings, but I am proud that I can take a medal home and put it around my mother's neck."
Rojas, whose world record is a massive 15.74m, was eighth with just 14.33m and three fouls through five jumps, throwing her hand up in frustration with each failed attempt. The biggest upset of these championships seemed imminent.
"My last attempt was proof of the hard work I have done - my mental state and my self confidence," she said.
Rojas gave herself a very animated pep talk before taking off down the runway and then, after landing what appeared to be around the 15m mark in the pit, squeezed her eyes shut hopefully before the winning distance was posted.
