The South African Institute for Drug-free Sport (SAIDS) have confirmed Gilbert's doping violation and subsequent ban from all sport handed down by CAS on their official website.
"The Court of Arbitration for Sport (CAS) has imposed a four-year ban from all sport on the Cycling South Africa athlete, Gordon Gilbert, following an appeal by the World Anti-Doping Agency (WADA) on an anti-doping rule violation sanction of 6 months rendered by the SAIDS Independent Doping Hearing Panel," read a statement.
"Mr. Gilbert tested positive for Testosterone. His period of ineligibility began on 2nd March 2017 (the date his provisional suspension was imposed) and will serve until and including 1st March 2021."
The 35-year-old was on the books of Chiefs between 2008 and 2010, and made three appearances in the 2008/09 season before being loaned out to Moroka Swallows the following campaign.
He later went on to play for Mpumalanga Black Aces, but that too did not last long as he was released after 18 months.
Former Orlando Pirates midfielder Thandani Ntshumayelo faces a similar ban of four years from football, after testing positive for cocaine in 2016.