Mollie Hughes, 26, began her climb with climbing partner Jon Gupta of Mountain Expeditions at 8.30pm and battled temperatures of -30C (-22F) on her journey to the summit, which she reached at 4.45am on May 16 just as the sun was rising.
Her arduous climb up the north side of Everest followed a similar feat up the south side of the mountain.
She said: “We set off at 8.30pm and when we got to the summit it was 4.45am. The sun was just rising and it was just elating when it rose just as we reached the top.
“It was so hard, especially when you are just 10 metres away from the summit and you can see it. When we got there I just hugged our guide and hugged Jon. It was overwhelming.”
She says a talisman blessed in a Puja ceremony before she set off provided her with the strength to keep going when she was inches from the summit.
The Puja was blessed before she set off and was one of the things she kept close to her despite climbing and even sleeping while wearing an oxygen mask.
Ms Hughes added: “They give out these necklaces for you to take at a Buddhist blessing ceremony before you set off.
“I’m not religious but when you are up there and everything is so desperate, you need something to hold on to.
“You’ve just got to separate your life from that moment because you are there to do a job.”
The 8,848m climb from camp three on the north side made Ms Hughes, who is originally from Torbay, Devon, but lives in Edinburgh, the youngest woman to tackle the climb from both sides of the mountain.
The feat followed a tough training regime including weeks climbing Scottish mountains such as the north face of Ben Nevis and four weeks acclimatising in Nepal before arriving at base camp.
Ms Hughes said the most difficult part was raising the £50,000 needed to take her to the top of Everest, including travel and costs for Sherpas and local guides for the area.
“It cost me almost £50,000, so it was a really big job getting the sponsorship together. It was great having Tiso come on board and was incredible having their support.”
Chris Tiso, chief executive officer of Tiso Group, principal sponsor of the expedition, said: “Over the weekend, the Tiso Returns to Everest 2017 expedition team received from Nepal the tremendous news that Mollie (Hughes) is in fact the youngest woman in the world to have climbed Mount Everest from both north and south.
“It’s a truly remarkable and inspirational feat.
“As a friend, fellow climber and her expedition sponsor, I am personally extremely proud that Mollie’s bravery and commitment to again successfully scale the world’s highest mountain with her close-knit team has culminated in her achieving an Everest world record.”