She was born on November 8, 1967 in KwaThema as the only daughter of the late Catherine Ndiyeni Ngwenya and Robert Mahlangu.
Mahlangu started her academic career at the Theo Twala Primary School and then proceeded to Tlakula High School.
Upon completing her matric, she did a business management course at Tlomoha College.
In 2014 she pursued a higher certificate in languages through the University of the Witswatersrand and before meeting her untimely death she was pursuing an advanced higher certificate in leadership governance and public management.
Cadre Thandi joined the ANC in the year 2000 in Ward 37, Vietnam branch.
In 2001 she was elected as the branch executive member and in 2002 she served as the treasurer of the ANCWL in her branch until 2009, where she was elected to be branch deputy chairperson.
In 2009 she was later re-elected as the branch executive member of the ANC in Ward 37, which is now known as Ward 85.
Mahlangu was elected in 2010 to serve in the ANC Zonal Committee of David Bopape. In that same year she transferred her membership to Branch 78 in Selope Thema.
Cadre Thandi also served as the deputy secretary of the ANC Ekurhuleni Regional from 2011 until 2014.
She served as the chairperson of the ANCWL in Margret Gazo branch (Ward 78) from 2012 until her passing and was elected as the chairperson of the ANCWL Selope Thema Zone.
In May 2014 Thandi Mahlangu was deployed by the ANC as a member of the Gauteng Provincial Legislature, where she took the role of whip in the National Council of Provinces.
From June 2014 until February 2015 she was responsible for the Benoni Parliamentary Constituency .
In March 2015 she moved to take responsibility of the Nigel, Duduza and Tsakane Parliamentary Constituency office.
Mahlangu leaves behind her father, Robert Mahlangu, two daughters, Zanele and Gugulethu, two grandchildren, Aulethu and Lethabo, her family and friends.
The funeral service will be held at the KwaThema Community Hall at 8am and the cortège will leave for the Vlakfontein Cemetery at 11.30am.
