Oluyemisi started her career at EKHA Agro Farms Limited as the first executive director. She then briefly worked as a project manager at Nigerian Breweries before pursuing her own business. In 2012, she developed her initial farming project in Alayide Village, Ado-Awaye, into a successful cassava processing company that supports smallholder farmers. Psaltry is recognized for producing cassava starch, flour, and glucose, and was the first in Africa and second globally to create cassava-based sorbitol. The company benefits over 100,000 farming families within 200 km of the plant and offers significant job opportunities in Iseyin LGA, Nigeria.

Beyond her work at Psaltry, she holds positions on the board of the IITA-BIP and serves as president of the Large-Scale Starch and Derivatives Producers Association (LSSDPA). 

She has participated in several national and international committees, including the Presidential Committee on Cassava Development and the FAO expert consultation on cassava processing. In recognition of her significant contributions to the Agriculture Transformation Agenda (ATA) under Dr. Akinwumi Adesina, the former Minister of Agriculture, she received distinguished honors from the Nigerian government in 2014. Her leadership in transforming agriculture continues to inspire change in the sector. Additionally, she participated in the Seed Transformation Programme at Stanford University and obtained a business management certificate from El Camino College in California. Oluyemisi is also an alumna of the U.S. Department of State's African Women Entrepreneurship Program (AWEP) in Washington, D.C.