Four gunmen sprayed his car with bullets in the city centre at 7pm (1600 GMT) before fleeing, said al-Hadidi on Sunday from Kirkuk general hospital.
He said he was wounded in the leg and that his driver suffered several "serious wounds”.
Al-Hadidi, a 48 year-old trader, became deputy governor of the city after US-organised elections for a local city council last May.
Kirkuk, which sits on major oil reserves, has been hit by a spate of attacks on Iraqi police and US occupation forces since October. But Sunday's was the first assassination attempt on a US-backed Iraqi official in the city.
In September, a member of the US-appointed Iraqi Governing Council, Aqila al-Hashimi, died of her wounds after being shot.
Meanwhile, several loud explosions rang out in Baghdad on Sunday night, rattling windows in the centre of the Iraqi capital, reported witnesses.
The US military had no immediate information on the cause of the blasts.
Earlier, a large explosion hit a Baghdad street near the headquarters of the US-led administration, but soldiers on the scene said there had been no casualties.
The troops were investigating to see whether the blast was caused by a bomb or a mortar or rocket attack. Damage was minimal apart from a small crater in the pavement.
Several times this month, resistance fighters have fired mortars or rockets at the headquarters of the US-led occupying administration in the capital.