She was involved in various public interest litigation in securing the electoral and democratic governance and processes in Kenya as well entrenching human rights in the society. Before that she was an intern at the Kenya Human Rights Commission where she worked on the Economic and Social Rights of women working for multinational companies in Kenya and Kenyans who would be affected by the large infrastructural projects being taken on by the Kenyan government such as the LAPSSET project. She volunteered with the Law Foundation of Silicon Valley where she worked on drafting court briefs for persons unlawfully and unprocedurally evicted from their homes in small claims courts in California, USA.
Achieng has a law degree from the University of Nairobi and a post graduate diploma in the Advocates´ Training Program from the Kenya School of Law.