Oluchi Onweagba had come into modeling after a family friend had persuaded her to enter M-Net's Face of Africa competition. She ended up winning the competition.

Onweagba's first name in her native Igbo language means "God's Work".[1][3] Her father was a civil servant, and her mother was a nurse.[1] She and her siblings (two brothers and a sister) lived on Ayilara Street, Ojuelegba, in Surulere, a low-income area of the sprawling Lagos (the Nigerian commercial capital) metropolis. She spent her high school years as a good student, and enjoyed playing tennis and ping pong. Supposedly, she was discovered while she was selling bread on the streets of Lagos in order to make ends meet.

In August 2005, she married her longtime companion, Italian fashion designer Luca Orlandi[4]. On April 25 2007 their son Ugochukwu was born.

She was urged by a family friend to enter into the M-Net Face of Africa preliminary screening at the M-Net office in Victoria Island, Lagos which she scaled through. The agency immediately groomed her to be one of Nigeria's entrants for a model competition, the M-Net Face of Africa (now called the Nokia Face of Africa). This despite the fact that, growing up, she had maintained a relative ignorance towards fashion and modeling. With the support of her family and friends, she decided to compete in the inaugural edition of the Face of Africa in 1998. This was the first-ever continent-wide model competition, as opposed to a mere beauty pageant, and was organized by the South African subscription television channel M-Net in collaboration with Elite Model Management. With her slim, tall figure, and her natural beauty, she captivated the judges, and she handily won the competition. She was just seventeen years old. Elite Model Management awarded Onweagba a three-year modeling contract, and a whirlwind life as a highly-sought-after fashion model began.

Moving to New York City, where she is currently still living, she began to make an impact. Onweagba graced the covers of Italian Vogue, i-D, ELLE, Untold, and Surface, and she also was featured in Nylon, Marie Claire, Allure, and other national editions of Vogue around the world. She also became the face of the campaigns for Gianfranco Ferré, Victoria's Secret, Gap, Express, Banana Republic, and Ann Taylor. Onweagba's runway experience has been with John Galliano, Christian Dior, Costume National, Chanel, and Giorgio Armani, amongst others, in London, Milan, Tokyo and Paris. She has worked with such high-caliber photographers as Steven Meisel, Nick Knight, and Patrick Demarchelier.

As her career took off, she did not forget her roots and attempted to give back to society. As one of the most high profile international models of Nigerian origin, she tries to serve as a role model for other aspiring talents in the west African country, especially young girls. She volunteers her time and her image for such NGOs as LEAP Africa (an entrepreneurship incubator) and NIPRO. She also is continuing her higher education, having studied for an associate's degree in the New York City educational system.

After her three-year contract with Elite expired, she signed with DNA Model Management. A highlight of her career so far was when she was featured in the Sports Illustrated Swimsuit Issue four times, from 2005 to 2008.

In 2008, she launched a modelling agency in South Africa, OModel Africa, with offices in Johanesburg and recently in Cape Town. The 2008 winner of M-Net Face of Africa, Kate Tachie-Menson, was awarded a US $50,000 modelling contract by OModel Africa.

In 2009, Onweagba is expected to host the inaugural West Africa's Next Top Model.