De Jager attended Langenhoven High School in Riversdale, Western Cape.
[1] De Jager was the DA's Shadow Mayoral Committee Member for Transport in the city.
In February 2017, De Jager was appointed as the Member of the Mayoral Committee for Environmental and Infrastructure Services, replacing Anthony Still.
[5] In April 2021, De Jager denounced Castro Ntobeko, an African National Congress member and employee of the Gauteng Department of Cooperative Governance and Traditional Affairs, for celebrating the death of four gay men and called for his immediate suspension.
[7] De Jager criticised the ANC in June 2021 during Pride Month for refusing to fly the Rainbow flag at the Johannesburg City council.