De Wilde was born in Zele, East Flanders. At the age of nine he entered local Eendracht Zele's youth system, joining the famous K.S.K. Beveren goalkeeper school in 1980. He then signed for R.S.C. Anderlecht after five full seasons, where he became a legend; during his first stint he won four national championships, three Belgian Cups and two Supercups.
In 1996, de Wilde left Brussels and his country and joined Sporting Clube de Portugal but, after losing first-choice status to youngster Tiago, returned home to Anderlecht in April 1998, for the rest of that campaign and five more (being first-choice until his last year).
In January 2004, after a brief spell in Austria with SK Sturm Graz, de Wilde joined, at 39, K.S.C. Lokeren Oost-Vlaanderen, for his final two seasons as a professional. He did play however during two months (April–May 2005) for lowly K.F.C. Verbroedering Geel.
Upon retiring in June de Wilde immediately rejoined former side Anderlecht, as a goalkeeping coach.
De Wilde was on squad for the Belgian national team in three FIFA World Cups: 1990, 1994 and 1998. He played the first of his 33 games with the Red Devils against Denmark in a 1989 friendly, coming on as a substitute for Gilbert Bodart at half-time.
In the first two World Cups, de Wilde acted as backup to legendary Michel Preud'homme but, after the latter's retirement he became first-choice, playing in the 1998 edition. His last international appearance was a sour one, as the match against Turkey at the UEFA Euro 2000 was lost by the hosts 0–2 and he was sent off with seven minutes to go (previously, he hesitated and lost the ball to opposing striker Hakan Şükür, who opened the scoresheet), as Belgium was eliminated in the first round.
De Wilde begun working with the Belgian under-21s in 2012, still as a goalkeeper coach.
- Belgian Pro League: 1983–84
- Belgian Cup: 1982–83; Runner-up 1984–85
- Belgian Supercup: 1984; Runner-up 1983
- Belgian Pro League: 1990–91, 1992–93, 1993–94, 1994–95, 1999–2000, 2000–01
- Belgian Cup: 1987–88, 1988–89, 1993–94
- Belgian Supercup: 1991, 1993, 1994, 1995, 2000, 2001; Runner-up 1988, 1989
- Belgian Goalkeeper of the Year: 1994, 2000