Okelo joined the
Barclays Bank management trainee program in July 1967 after several unsuccessful applications, becoming the first African woman to enter the program. The training involved two years of
diploma studies in banking at the British Institute of Bankers in London, where she lived from 1967 to 1969. While working at Barclays Okelo founded the Barclays Bank Women's Association to support female bankers. In the early 1980s she co-founded the
Kenya Women's Finance Trust (KFWT), an affiliate of
Women's World Banking, with her sister
Christine Hayanga. Okelo worked full-time at Barclays until 1985, when she was appointed the first African regional representative to Women's World Banking. In 1987 she moved to
Abidjan in
Côte d'Ivoire to serve as the first female senior adviser to the president of the
African Development Bank, and in 1990 she was appointed the vice-president of Women's World Banking. In 1978 Okelo and her husband established Riara Gardens Academy, a
private nursery school that initially served 8 students and operated out of Okelo's home. Later renamed the Makini School, the operation expanded throughout the 1980s to cover all levels of
primary education after erecting a dedicated school building in 1982. In the 1990s the operation split into three schools (Makini Lower Primary School, Makini Middle Primary School, and Makini Upper Primary School) occupying separate buildings and becoming collectively known as Makini Schools. Makini Schools expanded to offer
secondary education in 1997, and an
International Baccalaureate (IB) program was launched in 1998. ==Personal life==