Mike Perham grabbed the record Thursday after sailing 28,000 miles (45,000 kilometers) to cross the finish line off the coast of Cornwall, in southern England, after a mere nine months.
Perham is a few months younger than Zac Sunderland, from Thousand Oaks, California, who claimed the youngest solo crown in July when he completed a similar trip in 13 months.
Perham's boat, a 50-foot (15-meter) racing yacht called Totallymoney.com in honor of his sponsor, completed the trip at 9:55 a.m. (0855GMT) Thursday morning. He sailed with assistance - which means he was alone but stopped for repairs.
The teenager was then joined by his father Peter, who told The Associated Press that they "were just enjoying each other's company" en route to the coastal city of Portsmouth, where a party was planned for their arrival Saturday.
Perham, who set off in Nov. 18, celebrated his 17th birthday deep in the Indian Ocean. His grueling trip was blighted by autopilot failures, rudder problems and wild weather that repeatedly forced him to stop for repairs.
During a stop in Cape Town, South Africa, Perham got a chance to meet up with Sunderland, as well as 75-year-old Japanese yachtsman and serial circumnavigator Minoru Saito, the oldest man to finish a solo, nonstop around-the-world voyage.
While waiting for parts to repair his rudder in Tasmania, Perham took a brief trip to Brisbane, Australia, to meet Jessica Watson, the 16-year-old girl who also hopes to make it around the world.
After sailing above New Zealand and across the Pacific, Perham was towed through the Panama Canal and then cut across the Atlantic, heading for home.
Well-wishers tracked Perham's progress through his blog, where he chronicled his many mishaps - one entry is entitled "an unexpected swim" - and his impatience with what seemed to be an unending diet of freeze-dried food.
In an entry dated Thursday, Perham said the final leg of his trip "does feel a bit weird."
"I feel like I just want it to keep going, so I can have many more adventures," he wrote. On the other hand, he couldn't wait to see his father again.
"I'm very much looking forward to the reunion and his cheesy smile and all the rubbish jokes he brings along," Perham wrote.
Guinness World Records spokeswoman Amarilis Espinoza said, pending some verification, Perham would be certified as the "youngest sailor to circumnavigate the globe solo and unsupported."
Guinness had originally said Perham had been supported - accompanied by his father in a boat following behind him - but Espinoza said that was a mistake.
Perham may be young, but he's no stranger to spectacular sailing adventures. In January 2007, he became the youngest person to sail solo across the Atlantic at the age of 14.
On Friday in the Netherlands, 13-year-old Laura Dekker will find out at a court hearing if she is allowed to try to break Perham's record. Her parents are in favor of it, but a Dutch child protection agency is so concerned about the dangers of a solo voyage that it has asked for temporary custody of Laura so it can block her trip.
On the Net: http://www.totallymoney.com/sailmike/