He has held other major titles such as the Deputy Permanent Secretary of the Ministry of Foreign Affairs and Trade (MOFAT), and former chairman of the Brunei Japan Friendship Association.

[3] On 8 August 1994, at Rashtrapati Bhavan in New Delhi, Adnan, the High Commissioner-Designate of Brunei to India, presented his credentials to Shankar Dayal Sharma.

In the same year, Japan and Brunei inked an agreement to prohibit double taxation and combat fiscal evasion with regard to income taxes.

[1] After retirement, he remained actively involved in promoting bilateral ties through the Brunei Japan Friendship Association (BJFA), where he currently serves as Adviser I.

[11] The 2018 Spring Imperial Decorations awardees have been revealed by the Japanese government, and Adnan has been recognised for his noteworthy efforts to fostering goodwill and understanding between Brunei and Japan.