Khoo started his working career with Tenaga Nasional Berhad in 1976 at Tunku Ja’afar Power Station in Port Dickson. In 1979, he joined Malaysia Airlines as a security personnel and worked for nearly 15 years doing anti-hijacking and warehousing work. Khoo left the airlines industry and tried retailing and he was in the retail sector for 4½ years and served as a Floor Manager for Makro Cash & Carry Seberang Prai for 3 years.

He left the retail industry to embark on a career in the legal line. Worked for ILLIAYAS & Associates for 9½ years as an Office Manager. Subsequently, he left ILLIAYAS and joined Sheila Hussian Vijay & Partners as their Office Manager. Currently, Khoo serves as a Director cum Office Manager of the Company.