Matt Guthmiller, 19, completed the more than 29,000-mile journey in a leased single-engine airplane late Monday night when he touched down at Gillespie Field in El Cajon, California.
Guthmiller made about two dozen stops in 14 countries during the journey that began May 31, according to his mother, Shirley, who greeted her son after his 16-hour final leg flight from Honolulu, Hawaii.
"Of course he looked tired," Shirley Guthmiller said in a telephone interview. "I'm very relieved he is home, but I wasn't worried."
The Massachusetts Institute of Technology engineering student was sleeping late Tuesday morning, she said.
Matt Guthmiller took an early interest in aviation and was 16 when got his pilot's license.
"As a little kid, he was afraid to go down to the basement," said his father, Allen Guthmiller. "It's amazing how kids change. Now he's not afraid of anything."
Guthmiller's parents said he's sending documentation to Guinness World Records, which must confirm that he broke the record.
Jamie Antoniou, the senior public relations manager at Guinness, said Guthmiller was approved to try and break the record before he left. Antoniou said Guinness expects to know for sure whether he broke it by Thursday.
The previous record was set by Jack Wiegand, who was 21-years-old when he circumnavigated the globe in about two months in 2013.
Australian Ryan Campbell claims he broke Wiegand's record when he circled the globe last summer at age 19 years, seven months and 25 days old. Antoniou said Campbell applied to break the record but didn't send in his evidence until "very, very recently." She said the records team is assessing the evidence, but it's still missing some.
Shirley Guthmiller said Campbell helped her son in planning the trip. Guthmiller began in El Cajon and headed for his hometown, where he graduated from high school last year.
"He made his first stop in Aberdeen and then headed out for the rest of the world," Allen Guthmiller said.
He kept in daily contact with his parents by satellite telephone. He also routinely posted updates on social media.
"I'm proud of him and I really wasn't worried," his father said. "He had a good plane and a good plan."
Guthmiller's flight will help raise money for Code.org, a nonprofit website that helps teach people about computer coding, his father said.