"It is with great sadness and sorrow that we mourn the martyr of the nation, Juma Mohammed Abdullah Al Kaabi, who gave up his soul for the sake of humanity," the state-run WAM news agency reported, quoting a statement by the Ministry of Presidential Affairs.
Juma was wounded in the blast last month that also killed 12 people including the deputy provincial governor and five UAE diplomats. The ambassador was transferred by military plane to Abu Dhabi in the UAE for treatment.
Provincial police chief Abdul Raziq had blamed Pakistan's powerful spy agency Inter-Services Intelligence (ISI) and the Taliban-allied Haqqani network for the attack.
The Taliban had denied carrying out the blast.