Mahama Cho secured a place for Britain in the Tokyo 2020 heavyweight division by finishing second at the World Taekwondo Grand Slam in China.
The 30-year-old defeated reigning world champion Radik Isaev in the quarter-finals, but lost to South Korean Kyo-don In in a tight final.
The result means Team GB will have five fighters at an Olympics for the first time next year.
Jade Jones was runner-up in the -57kg division for the second year in a row.
The two-time Olympic champion lost to China's Lijun Zhou in the final.
Cho missed out on automatic qualification through the world rankings after a first-round loss at the Grand Prix final earlier this month.
However, one athlete from each of the eight Olympic divisions at the Grand Slam had the chance to secure a berth for their nation at Tokyo 2020, and with Cho's conqueror having already qualified, Britain were awarded the men's heavyweight place.
Jones (-57kg), Lauren Williams (-67kg) , Bianca Walkden (+67kg), Bradly Sinden (-68kg) had already secured places through their world rankings.
They are expected to be officially named in the Team GB squad in May next year and although Cho is the favourite for selection at +80kg, team-mate Lutalo Muhammad is also in contention.
The Rio 2016 Olympic silver medallist won the French Open last month and next year's European Championships could be crucial in deciding which athlete is ultimately chosen for the 2020 Games.
"Not only am I delighted with securing five Olympic spots, but also the manner of performances along the way," GB Taekwondo's performance director Gary Hall told BBC Sport.
"Two of our athletes are ranked number one in the world, another two are ranked second and we have three reigning world champions.
"I'm confident we will be taking our best-ever team to an Olympics."
Three-time world champion Bianca Walkden will look to secure her third successive Grand Slam title when she contests the +67kg division on Friday.