Mabel Segun was a freelance radio and television broadcaster for twenty-seven years, contributing at first to the schools programmes of the pioneer Western Nigerian Television Broadcasting Service based in Ibadan and the national programmes of the Nigerian Broadcasting Corporation (NBC), later renamed Federal Radio Corporation (FRCN) based in Lagos.

In Lagos, she broadcast in almost all the departments of the Radio Nigeria Service including talks, features, women's and children's, sports and news. Her most outstanding contribution was the weekly social satire which went by various programme titles: Off Beat Views, Oddity, In the Round, This and That. This highly popular programme ran for fourteen years (1961 - 1974). The talks were witty and anecdotal and contained amusing vignettes of Nigerian's including the speaker. She satirized the medical professions cult-like behaviour, lawyer's quibbling, hypocrisy in the church, the vanities of extended burial ceremonies, nepotism, polygamy (ancient and modern) and the lethal disogarnised Lagos traffic.

When the Voice of Nigeria Service for foreign listeners was started by FRCN, Mabel Segun was invited to contribute a weekly newsletter for foereign listeners. This was aired for six years (1964 -1970). Modelled after the famous Alistair Cooke Series - Letter From America - it commented on various news items which she enlivened with a touch of humour. FRCN recognised her outstanding contributions tot he development of radio broadcasting in the country by naming her "Radio Nigeria Artiste of the Year 1977".

Mabel Segun was involved in television both as an artiste and as a producer. From the late 1960s to the mid-1970 she was often invited to moderate Viewpoint, a Nigerian Television discussion programme which drew public attention to the problems faced by women in a changing socio-cultural environment. She also rewrote folktales for the children's programme and presented sports promoting programmes among young children.

Her work as a television producer was done under the auspices of the Federal Ministry of Education whose broadcasting unit she headed from 1967 to 1970. She revolutionized the teaching of English on television by introducing into her primary school lessons interactive elements such as games and playacting. Under her supervision the science lessons were also made more exciting and thought-provoking.