The best game of Buchwald's career was probably the final of the 1990 FIFA World Cup where he effectively marked the skilled footballer Diego Maradona, earning him the nickname "Diego". He was also part of Germany's disappointing 1994 FIFA World Cup squad and collected in his career 76 caps.
Buchwald began his professional football career in 1983 with VfB Stuttgart. He played 325 games in the German Bundesliga for this club, scoring 28 goals. The low-point of his career was in 1986 when coach Franz Beckenbauer did not include him in his team for the World Cup in Mexico. He was however part of the squad which won the World Cup in Italy four years later.
His personal highlight in his Bundesliga-Career was on the last day of play in the 1991–92 season, when he scored the deciding goal against Bayer Leverkusen that won Stuttgart the match and the Championship – just six minutes before the games' end.
In 1994 he signed with the Japanese team Urawa Red Diamonds before returning to Germany in 1998 to help Karlsruhe avoid relegation. He could not save the team and after one more season playing in the second division he retired but stayed with the club as a director of sports.
After a stop with the Stuttgarter Kickers (again as director of sports) he went back to Japan where he was managing his old club. He led his team to the "closing" championship. In 2005, won the title on Emperor's Cup. In 2006, he won the title on both J-League and Emperor's Cup
Buchwald then returned to Germany to become manager of Alemannia Aachen. After five months on duty he was fired by club management on 26 November 2007.
On 1 November 2010, Buchwald returned to the Stuttgarter Kickers as a member of the board responsible for the first team. He took over as interim manager in November 2012 after the sacking of Dirk Schuster, before relinquishing this duty a month later when Gerd Dais was appointed.