Zenit St Petersburg midfielder Shirokov grabbed his first international goal to give Russia a perfect boost ahead of their UEFA EURO 2012 qualifying campaign which starts at Andorra on 3 September.
Russia, who were playing their first match since March, when they recorded a 1-1 draw in a friendly at Hungary, and first since previous coach Guus Hiddink left for Turkey, were in front after six minutes. Shirokov found the target with a close-range shot after Bulgaria goalkeeper Nikolai Mihailov failed to cut out a free-kick from Arsenal star Andrei Arshavin.
Bulgaria went looking for the equaliser and came close in the 34th minute with Russia goalkeeper Igor Akinfeyev saving Ivelin Popov's close-range shot after being set-up by Martin Petrov's left-wing cross. In the 52nd minute, Arshavin fired a drive from just inside the box forcing Mihailov into a diving save.
Bulgaria than had another opportunity six minutes later when a right wing cross from Stanislav Manolin fell to substitute Martin Kamburov and then Dimitar Rangelov, but neither were able to get the vital touch.
Bulgaria begin their EURO 2012 qualifying campaign against England at Wembley on 3 September.