Germany ended South Korea's dream run with a 1-0 victory in the first semi-final, to reach the World Cup final for a seventh time on Tuesday.
Michael Ballack scored the winning goal 15 minutes from time, but he will miss Sunday's Yokohama final, against either Brazil or Turkey, through suspension.
Germany, who won the title in 1954, 1974 and 1990, were matched throughout a thrilling, end-to-end game by Asia's first representatives in the last four who were backed by a fervent crowd of 65,000.
Playmaker Ballack, booked in the 71st minute for a foul, scored the winner four minutes later, following up from close range after his initial effort from an Oliver Neuville cross was punched out by goalkeeper Lee Won-jae.
Brazil and Turkey play the other semi-final on Wednesday in Saitama, Japan. Germany have never played the four-times winners Brazil in the 72-year history of the World Cup.
South Korea fought bravely and their defence held out well but they had few chances of their own after an eighth minute save by Oliver Kahn.
Germany captain Kahn, their saviour in the quarter-final defeat of the United States, came to his team's rescue again with a spectacular diving safe from Lee Chun-Soo in a relatively uneventful first half.
The co-hosts pressed hard in the opening stages but a compact German team then gradually took control, relying on long balls aimed at top striker Miroslav Klose.
South Korea, chasing one of the biggest upsets in World Cup history with a place in the final after starting 100-1 outsiders to do so, never quit but ran up against a German defensive wall in the closing stages.
They had earlier beaten European giants Portugal, Italy and Spain on their way to a last four place, sparking national delirium.
First as unified nation
Germany's 1-0 victory took them into their seventh final and their first as a unified nation.
Their previous six finals, all as West Germany, were:
1954 West Germany 3 Hungary 2, Berne
1966 England 4 West Germany 2 after extra time, London
1974 West Germany 2 Netherlands 1, Munich
1982 Italy 3 West Germany 1, Madrid
1986 Argentina 3 West Germany 2, Mexico City
1990 West Germany 1 Argentina 0, Rome