[2] After Magufuli's death in March 2021, Mabeyo played a major role in ensuring a smooth transition of power to the new President, Samia Suluhu Hassan.

[4] He formally joined the Tanzania People's Defense Force (TPDF) on 1 January 1979, attended the student officer course, and received a commission in 1980 as a Sub Lieutenant.

[5][6] In February 2019, Mabeyo personally visited Njombe Region to assist in the investigation of the murder of ten children who had probably been ritually tortured and killed.

[10] In May 2020, the TPDF under Mabeyo deployed troops to the Tanzanian-Mozambican border to counter raids of Islamist rebels that were waging the insurgency in Cabo Delgado.

[12] Tanzanian President John Magufuli unexpectedly died in March 2021, leaving Samia Suluhu Hassan as his de jure designated successor.

According to various sources, including CCM insiders, gathered by The EastAfrican, Mabeyo strongly defended the constitutional stipulations regarding the transfer of presidential powers and supported Hassan.