Datuk Hiswani retired from the Ministry of International Trade and Industry (MITI) in February 2016 after serving for about 12 years. Her last post at MITI was Deputy Secretary General (Trade). 

After retirement, she served as Advisor to MITI until December 2016 as Chief Negotiator to the Regional Comprehensive Economic Partnership (RCEP). Prior to MITI, Datuk Hiswani has also served in Department of Fisheries, Ministry of Agriculture, Ministry of Primary Industry, Ministry of Science, Technology and the Environment (Director of Conservation and Environmental Management) and the National Institute of Public Administration (INTAN). 

She has also served as Minister Counselor and Malaysia’s Ambassador to the World Trade Organisation (WTO) based in Geneva, Switzerland from 2007 and 2012.

She currently serves on the Board of the Malaysian Green Technology and Climate Change Corporation (MGTC) as an independent director. She also chairs the Green Technology Malaysia Alliance (GTMA), a holding company of MGTC. 

Datuk Hiswani was appointed as a Reef Check Malaysia trustee in 2018.