The 20-year-old, ranked 100th in the world, will join an elite group, including Pete Sampras, to make their debuts in the final of the team event that Britain last won in 1936.
The last time Britain reached the final in 1978, John McEnroe played his first Davis Cup singles rubber for their U.S. opponents, winning both his matches.
The visiting team's talisman, world number two Andy Murray, will face Ruben Bemelmans in the second rubber of the best-of-five contest on a drop-in claycourt at the 13,000-capacity Flanders Expo in the medieval city of Ghent.
Edmund, who won a recent claycourt Challenger event in Buenos Aires, was picked by captain Leon Smith ahead of the more experienced James Ward.
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Belgium captain Johan Van Herck, spearheading their bid to win the Cup for the first time, also caused surprise by selecting world number 108 Bemelmans ahead of 84th-ranked Steve Darcis to face Murray on the opening day.
Saturday's doubles will see Murray and older brother Jamie take on Darcis and Kimmer Coppelmans.
The make-up of the reverse singles, which will see world number 16 Goffin play Murray, could be changed, with Darcis and Ward potentially coming in to contest a decisive fifth rubber.
Edmund's selection was not unexpected but it will be a massive step up as he looks to become the first debutant to win a live rubber in the Davis Cup final -- a feat beyond 14-times grand slam champion Sampras for the U.S. in 1991.
"This will be the biggest crowd I've ever played in front of, it's a new experience for me," Edmund, looking composed at a packed news conference, told reporters.
"It's exciting to play my first match for my country."
Captain Smith said it had been a "hard decision" but he had been swayed by Edmund's ranking and form on clay.
Murray, provider of eight of Britain's nine points on the way to the final, said he was "pumped" for the tie.
"There are nerves obviously, but that's a positive thing. When I'm not nervous that's when I worry a little," the 28-year-old said.
Facing Murray, Belgium, who reached their only final in 1904 when losing to Britain, are inevitably underdogs but Van Herck believes the crowd will be like an extra player.
"We need our fans to get on their backs a bit, get the crowd as involved as much as we are allowed...it's an advantage we have to take," he said.
(Editing by: Ossian Shine and Ian Chadband)
