Playing in front of his club fans at Fiorentina’s Artemio Franchi stadium, Gilardino put the Azzurri on their way in the 11th minute.
Daniele De Rossi doubled Italy’s lead 11 minutes later and Antonio Cassano made it 3-0 before the half-hour mark.
Substitute Fabio Quagliarella added another in the 80th-minute before Andrea Pirlo capped off a wonderful evening for the Azzurri at the death.
Italy coach Cesare Prandelli got a standing ovation as he returned to Florence, where he coached Fiorentina for five years before joining the national team this summer.
In the other Group C clash, Nikola Zigic grabbed a late equaliser as Serbia secured a home draw against Slovenia.
A dramatic injury-time winner from Stephen McManus saved boss Craig Levein from a disastrous competitive home debut and prevented Scotland’s Group I campaign taking a severe blow against Liechtenstein at Hampden Park while Czech Republic suffered a shock 1-0 home defeat to Lithuania.
Portugal’s difficult start to their Group H campaign continued as they fell to defeat against Norway in Oslo.
Carlos Queiroz’s side were held to a 4-4 draw with Cyprus in their opener and were unable to respond after Erik Huseklepp gave the hosts a 21st-minute lead at the Ullevaal Stadion, leaving them languishing in fourth place. Denmark beat Iceland 1-0.
In Group A, Germany continued their smooth start with a comprehensive 6-1 victory over Berti Vogts’ Azerbaijan in Cologne.
Substitute Heiko Westermann made the breakthrough in the 28th minute and goals from Lukas Podolski and Miroslav Klose in first-half stoppage time made the result safe.
Rashad Sadygov’s own goal eight minutes after the interval stretched the hosts’ advantage and, although Vagif Javadov pulled one back four minutes later courtesy of an error by Manuel Neuer, further goals in the final five minutes from Klose and Holger Badstuber sealed the rout.
Group rivals Turkey made it two wins out of two thanks to a thrilling victory over battling 10-man Belgium in Istanbul. The visitors took the lead through Daniel Van Buyten just before the half-hour mark but Turkey pulled level through Hamit Altintop early in the second period.
The dismissal of Vincent Kompany just after the hour hit Belgian hopes and Guus Hiddink’s side capitalised when Semih Senturk fired home.
Van Buyten’s second of the night put Belgium on course for an unlikely point before Arda Turan popped up to win it inside the final 15 minutes as Turkey maintained their perfect start to the group following Friday’s victory over Kazakhstan who lost 2-0 at home to Austria in last night’s other game.
In Group D, France secured a 2-0 win at Bosnia-Herzegovina while Belarus were unable to recreate the Paris heroics but did secure a creditable 0-0 draw against Romania in Minsk while Albania beat Luxembourg 1-0.
In Group E, Klaas Jan Huntelaar hit as brace as Holland made heavy weather of defeating a spirited Finland side 2-1 in Rotterdam.
Earlier, it was revealed that Arsenal’s Dutch striker Robin van Persie will be out of action for six weeks.
Zlatan Ibrahimovic scored twice as Sweden shrugged off the first-half dismissal of defender Olof Mellberg and maintained their 100% start in Group E with a 6-0 rout of San Marino.
In the other game, Hungary beat Moldova 2-1. In Group F, there were two scoreless draws, Georgia at home to Israel and Croatia hosting Greece while Latvia won 2-0 at Malta.
In England’s Group G, Bulgaria lost once again, turned over 1-0 at home to Montenegro.