"Mom, I'm calling you from the top of the world," Jordan Romero, of Big Bear, said to his mother, Leigh Anne Drake, she recalled, the BBC reported.
The boy, climbing with his father and three Sherpa guides, claimed the record for the youngest to reach the peak of the world's highest mountain at 29,035 feet above sea level. That distinction had been held by a 16-year-old Nepalese boy.
Jordan has reached summits on six continents, including Mount Kilimanjaro in Africa as a 10-year-old.
On Jordan's blog, a posting said the climbers' "dreams have now come true. Everyone sounded unbelievably happy."
The team left Nepal's capital, Kathmandu, last month, for the base camp on the Chinese side of the mountain. Nepal requires Mount Everest climbers to be at least 16 but China has no age restrictions.
Before leaving for the expedition, Jordan wrote, "Every step I take is finally toward the biggest goal of my life, to stand on top of the world."
And, his mother told the BBC, he had promised to do some homework between climbs.