Sidek bin Ali is a Bruneian diplomat who formerly held the position of ambassador to Laos from 2006 to 2008, high commissioner to India from 2008 to 2020, and Singapore since 2020.

[2][3] In March 2006, he welcomed Crown Prince Al-Muhtadee Billah and Princess Sarah during their state visit to Laos.

[2] When Sultan Hassanal Bolkiah and his delegation arrived at Palam Air Force Station on 20 December 2012, he welcomed them.

[9] As the newly appointed high commissioner to Singapore, Dato Sidek had a meeting with Al-Muhtadee Billah on 9 December 2020.

[11] On 18 July 2023, the Supreme Courts of Singapore and Brunei Darussalam signed a memorandum of understanding (MoU) to improve cooperation, communication, and coordination on matters pertaining to the avoidance and settlement of disputes.