She has served as the Principal Secretary State Department Of Broadcasting And Telecommunication, Ministry of ICT, Innovation and Youth Affairs since her appointment by former president Uhuru Kenyatta in January 2020.

[1] Prior to her appointment in the ICT docket, Koimett served as the Principal Secretary, State Department for Transport, Ministry of Transport, Infrastructure ,Housing, Urban Development & Public Works since her appointment in August 2018.

[2] She has also worked as the Director General Public Investment and Portfolio Management at the National Treasury.

[4] She has been responsible for the divestiture of parastatal companies either through the selection of a "strategic investor", or through the flotation of an IPO, on the Nairobi Stock Exchange.

[3] As Principal Secretary, State Department of Broadcasting and Telecommunications she oversees all the State Corporations under the Department, namely: As PS, Transport she was in charge of overseeing the Kenya Airways and all the State Corporations under the Department, namely: She has been a member of the boards of[4] Kenya Railways Corporation, Telkom Kenya, Mumias Sugar Company Limited, Nairobi Stock Exchange, Safaricom, and The African Trade Insurance Agency (ATI).