The Azzurri have stretched their lead at the top of Group B to seven points ahead of visiting Bulgaria, but the latter will feel that they should have got something out of the game. Just three World Cup qualifying games remain, and Italy will seal a place in next year's finals if they defeat Czech Republic in Turin on Tuesday evening.
With Riccardo Montolivo, Pablo Daniel Osvaldo and Mario Balotelli all suspended, 22-year-old Lorenzo Insigne was handed his first start as he supported Gilardino in a three-man attack along with Antonio Candreva. Thiago Motta was also back for the first time since the Euro 2012 Final.
Gilardino saw a snap shot saved inside the first minute, while Andrea Pirlo sent an effort into Row Z as Bulgaria took their time to settle. The visitors almost hit the front on 20 minutes with their first real chance. Ivelin Popov played in Alexandar Tonev, but the ball bounced off the turf and Gianluigi Buffon spilt the effort. Fortunately for Italy, no-one was on hand to pick up the rebound and Buffon eventually smothered the ball.
Gilardino put Italy in front seven minutes before the break. The Genoa frontman was lurking in the six yard box before heading home Candreva's cross from the byline. It was Gila's 19th international strike and a classic centre forward's goal.
Italy almost scored a second straight from the restart, but Gilardino's poor attempt at a chip was easily caught by Mihaylov. Less than a minute later, Bulgaria thought they had drawn level. Todor Nedelev's volley across the box was met by Popov sliding in, but Buffon somehow clawed it off the line and away to safety.
Bulgaria enjoyed their best spell of the game and felt they should have equalised on more than one occasion. Buffon showed great reflexes by palming Dimitar Rangelov's header off the line after he Bulgarian substitute had been on the pitch less than a minute.
The Balkan siege continued as Nedelev and Stanislav Manolev combined to carve the Italian defence wide open with a neat one-two before Nedelev bent a low 18 yard shot just past the far post. Gilardino intercepted a poor backpass ahead of Mihaylov, but was denied a second goal after Nikolay Bodurov ran back to hack the ball off the line.
The momentum eventually dropped as the heat and humidity started to rise. Italy retreated to keep hold of their lead and slow the game down and, as time ticked away, Bulgaria threw everything forward. Even Mihaylov came up for corners. Leonardo Bonucci almost gifted an equaliser at the death with a poor clearance, but the ball was headed into the side netting by the unlucky visitors.
Italy: Buffon; Abate, (Maggio 80) Bonucci, Chiellini, Antonelli; (Astori 63) Thiago Motta, Pirlo, De Rossi; Candreva, Insigne; (Giaccherini 64) Gilardino
Bulgaria: Mihaylov; Y Minev, Bodurov, Ivanov, V Minev; Dyakov; (Delev 75) Manolev, (G.Iliev 55) Nedelev, Gadzhev, Popov; Tonev (Rangelov 61)
Goals: Gilardino 38 (I)