Born in Bushbuckridge, Siwela spent almost three decades as a teacher and primary school principal in Mpumalanga.
She entered politics as a ward councillor for the ANC in the Bushbuckridge Local Municipality in 2000 and joined the provincial legislature in 2005.
[2] At the same time, from 2000 to 2005, she represented the African National Congress (ANC) as a ward councillor and Member of the Mayoral Committee in Bushbuckridge Local Municipality.
He named her to succeed Candith Mashego-Dlamini as Member of the Executive Council (MEC) for Agriculture, Rural Development and Land Administration.
[5][6] The opposition Democratic Alliance, criticising various aspects of the reshuffle, said that its "greatest concern" was the appointment of Siwela, whom it considered "a weak leader".
[13] At the same time, she remained in the Human Settlements portfolio until 17 August 2016, when Mabuza announced a reshuffle in the aftermath of recent local government elections.
Siwela was sacked from the Executive Council, to be replaced by Speedy Mashilo, and became an ordinary Member of the Provincial Legislature.
[16] Because she had been elected to national party office, the ANC's constitution required Siwela to step down as Deputy Provincial Chairperson in Mpumalanga.
[23] In the 2019 election, Siwela did not stand for re-election to the provincial legislature; instead, she was sworn in to a seat in the National Assembly, the lower house of the South African Parliament.
[24] She was also appointed to the Section 194 Enquiry into the Public Protector, Busisiwe Mkhwebane;[9] however, in June 2023, she recused herself from the enquiry in order to avoid bias in dealing with a related complaint laid by Mkhwebane in the Joint Committee on Ethics and Members' Interests, of which Siwela was also a member.