[5][7] He served as the General Manager with Maju Bangun Sdn Bhd, a subsidiary company of the Perak State Development Corporation from 1980 till 1987.

In 1989, he ventured into private business and sat on several companies listed on Bursa Malaysia Securities Berhad (known then as the Kuala Lumpur Stock Exchange).

[13] In 2020, when the Pakatan Harapan government crumpled due to Mahathir Mohamad's sudden resignation after trying to eradicate those who are involved in the Sheraton Move but failed.

Hamzah allegedly made the remark when campaigning during the Permatang Pauh by-election in August 2008, which subsequently saw Anwar’s return to parliament after a 10-year absence.

[5][15] In 2021, he was caught having a phone conversation with the soon-to-retire Inspector-General of Police (IGP) to allow him to internally transfer staffs and also enable him to have over certain jurisdiction of Polis Diraja Malaysia (PDRM) which will indirectly interfere with the operation.

[5] He acknowledged that the voice of the recording was his and stand being corrected as it is not unlawful despite IGP's comment on how politician's interference will make operations hard for the PDRM.