Born in
Rome, Tassotti played his first professional season with local club
Lazio in
1978–79, where he soon became a first team member the
following season, making his
Serie A debut on 5 November 1978. During his two seasons with Lazio, he made 41 appearances in Serie A and 47 in all competitions. during the
1983–84 season Following Lazio's and
AC Milan's relegation to
Serie B due to their involvement in the
1980 match-fixing scandal, he was called upon by the Milanese squad and transferred to the side, becoming a first-team member alongside captain and defender
Franco Baresi, as well as
Filippo Galli, during a dark period in Milan's footballing history, under manager
Nils Liedholm. He made his Milan debut on 24 August 1980, in Serie B, in a 1–0 home win over
Catania. Despite winning the
Mitropa Cup the following season, Milan were unable to remain in Serie A, finishing
third last, and were relegated once again to Serie B. Milan were able to win
Serie B again the following season to return to
Serie A. Although this was a fairly bleak period in the club's history, as they failed to dominate in the league or capture a trophy, the squad did reach the
Coppa Italia final during the
1984–85 season, and were able to regularly qualify for the European competitions, frequently finishing in the top half of the table. Tassotti became a central figure in the Milan squad of the late 1980s and early 1990s under
Arrigo Sacchi, and subsequently
Fabio Capello, usually wearing the number 2 shirt. He also won three consecutive Serie A titles with the club in the
1991–92,
1992–93 and the
1993–94 seasons, adding another during the
1995–96 season, in addition to the
1994 UEFA Super Cup and three consecutive Supercoppa Italiana titles between 1992 and 1994. In the 1991–92 season, Milan won the title unbeaten, scoring a record 74 goals, and remained undefeated for a record 58 matches in Serie A. In 1993–94, Tassotti once again helped Milan finish the league with the best defence, only conceding 15 goals. In his last few seasons at Milan under Capello, he began to be used less frequently, due to his advancing age and the emergence of
Christian Panucci in his position. Along with his teammate Baresi, Tassotti retired from the club at the conclusion of the
1996–97 season. In total, he made 429 Serie A appearances with Milan, scoring 8 goals, and 583 total club appearances, scoring 10 goals. ==International career==