At international level, Signori represented Italy 28 times between 1992 and 1995, scoring 7 goals, and took part at the 1994 World Cup, where they reached the final.

He then spent two short periods abroad: first in Greece in 2004 with Iraklis Thessaloniki; and then in October 2005 he signed a one-year contract with Hungarian team MFC Sopron to end his professional career.

Overall, he scored 188 goals in Italy's top division, the ninth highest in the history of the league, alongside Alessandro Del Piero and Alberto Gilardino.

[5][6] Signori was a fast, hard-working, and diminutive left footed striker, who was a prolific goalscorer, due to his powerful and accurate shot, which drew frequent comparisons with Luigi Riva in the Italian media.

[7][8][9][10][11] Alongside Siniša Mihajlović, he is one of two players to have scored a hat-trick from free kicks in Serie A, a feat which he managed with Lazio in a 3–1 home win over Atalanta, on 10 April 1994.

[11][14] Signori was sponsored by Diadora and used to squeeze his feet into boots that were too small for him, claiming that this improved his touch and accuracy on the ball.

[16][17] On 1 June 2011, Signori was arrested in connection with a football betting scandal, together with other former players such as Stefano Bettarini and Mauro Bressan.