Details of Bajkam's early life are unknown. He was one of the ghilman (military slaves, usually of Turkish origin) of the Daylamite warlord Makan ibn Kaki in northern Iran. Makan took care of the young Bajkam's training and education, something for which the latter showed his gratitude by adopting his patron's name as his nisba (surname). After Makan, Bajkam entered the service of Mardavij, founder of the Ziyarid dynasty, who came to control Daylam, Jibal and Tabaristan. Mardavij mistreated his ghilman, who consequently murdered him at Isfahan in January 935, an act in which Bajkam may have been complicit. After Mardavij's death, most of the ghilman in Ziyarid service dispersed. Bajkam and his fellow officer Tuzun assumed the leadership of a large group and, after first offering their services to the new governor of Jibal, Hasan ibn Harun, proceeded to the Abbasid court at Baghdad. At first, their offers were rejected by the court, where the Caliph's Hujari bodyguards jealously guarded their prerogatives, but the ghilman were eventually taken into the service of Muhammad ibn Ra'iq, governor of Basra and Wasit in southern Iraq. Now known as Bajkam Ra'iqi, Bajkam created a large military force under his command consisting of his own followers as well as additional Turks and Daylamites summoned from Jibal.
In early November 936, the Caliph al-Radi (reigned 934–940) bestowed the newly created title of amir al-umara ("commander of commanders") on Ibn Ra'iq, who was effectively granted absolute control over the Caliphate. This provoked the reaction of various provincial governors as well as that of powerful interest groups in Baghdad itself, such as the caliphal bodyguards. Against them, Ibn Ra'iq employed Bajkam and his Turkish supporters. With their aid, he managed to neutralize the Hujari and Saji guard units, after which, in February 937, Bajkam was rewarded with the posts of sahib al-shurta (chief of police) and governor of the eastern provinces.
Far more difficult and protracted was the war against the ambitious governor of Ahwaz, Abu Abdallah al-Baridi, who aimed to supplant Ibn Ra'iq. Al-Baridi's family was of Basran origin, and had served the Abbasids in various roles as officials before managing to assert a weak hold over Khuzistan. Ibn Ra'iq himself was defeated and forced to leave Basra to the Baridis, but Bajkam saved the situation by scoring two major victories, despite being outnumbered, that allowed him to take possession of Khuzistan. The hard-pressed al-Baridi now turned to his powerful neighbour, the Buyid ruler of Fars, Ali ibn Buya, for help. Ali's brother Ahmad soon took over Khuzistan, and Ibn Ra'iq was forced to offer possession of the province as an independent domain if Bajkam would recover it. Bajkam however was repulsed by the Buyid forces, and fell back to Wasit.
Ignoring Ibn Ra'iq's orders to retake Khuzistan, Bajkam remained at Wasit, and began plotting to depose Ibn Ra'iq himself. To this end, Bajkam began seeking allies: he offered the governorship of Wasit to the Baridis, and through the former vizier Ibn Muqla, who wished to avenge himself on Ibn Ra'iq for his own downfall and confiscation of his property, gained the covert support of Caliph al-Radi himself. In September 938, Bajkam led his troops from Wasit to Baghdad. Ibn Ra'iq tried without success to impede his advance by destroying the great dams of the Nahrawan Canal and flooding the plain, but Bajkam's army entered the Abbasid capital without opposition, and al-Radi immediately transferred Ibn Ra'iq's title of amir al-umara to Bajkam.
Despite the continued relegation of al-Radi to a ceremonial role, the relationship between the Caliph and Bajkam was strong, with al-Radi praising Bajkam for his harsh discipline and referring to the latter as his "protégé". Al-Radi was appreciative of Bajkam's respect for his position as Caliph, and promised his support for the amir al-umara.