In 2005, Siwela was sworn in to the
Mpumalanga Provincial Legislature, where she filled a casual vacancy in the ANC's caucus. She deputised
Jackson Mthembu and then
William Lubisi, who succeeded Mthembu as Speaker later in 2009.
MEC for Agriculture: 2013–2014 On 18 February 2013, Siwela was appointed to the
Executive Council of Mpumalanga by Mabuza, who was then in his first term as
Premier of Mpumalanga. He named her to succeed
Candith Mashego-Dlamini as
Member of the Executive Council (MEC) for Agriculture, Rural Development and Land Administration. 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". According to the party, Siwela's appointment was "surely a reward for securing Premier Mabuza's support with ANC structures in the Bushbuckridge region" and "signals a sad day for the
agricultural sector in Mpumalanga – a sector in which she has little or no knowledge, or sentiment."
MEC for Human Settlements: 2014–2016 Ahead of the
May 2014 general election, the ANC Provincial Executive Committee submitted Siwela as one of three possible candidates to stand as the party's candidate for election as Premier, though Mabuza was presumed likely to be re-elected. Pursuant to the election, Siwela was re-elected to the provincial legislature, ranked sixth on the ANC's provincial party list, and Mabuza appointed her to his second-term Executive Council as MEC for Human Settlements; she traded portfolios with
Andries Gamede.'''''' Upon taking office, she said that she would seek to involve her department in job creation, skills development, and
public–private partnership. She succeeded
David Dube in that position. 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.
Nasrec conference: 2017 In December 2017, Siwela attended the ANC's
54th National Conference at
Nasrec, where she was elected to a five-year term as a member of the party's
National Executive Committee. By number of votes received, she was ranked seventh of the 80 ordinary members elected to the committee. Because she had been elected to national party office, the ANC's constitution required Siwela to step down as Deputy Provincial Chairperson in Mpumalanga. The party said that an acting replacement would be appointed until the next provincial party elections. A permanent replacement for Siwela was not elected until April 2022, when Speedy Mashilo became Deputy Provincial Chairperson.
Speaker of the Mpumalanga Legislature: 2018–2019 In the aftermath of the ANC's national conference, Mabuza was promoted to become
Deputy President of South Africa. He was replaced as Premier by
Refilwe Mtsweni, who reshuffled the provincial cabinet. As a result of the reshuffle, the Mpumalanga Provincial Legislature elected new presiding officers on 22 March 2018, electing Siwela to succeed
Thandi Shongwe as the Speaker.
Bonakele Majuba was elected as her deputy. Siwela served in the Speaker's office until the
May 2019 general election, when
Busisiwe Shiba was elected to succeed her. == National Assembly: 2019–2024 ==