In 1953, Yokum was hired as a teller at the Langley Federal Credit Union in Hampton, Virginia. She took on the role of assistant bookkeeper before becoming the director of accounting. She completed a three-year course through the Credit UnionBusiness School in Wisconsin. She served as the credit union's assistant manager and in 1979 was appointed president and CEO. The National Association of Federal Credit Unions named her Credit Union Professional of the Year in 1983. During her tenure, the financial institution's assets grew from $76 million in 1979 to $1.6 billion in 2011. Yokum retired from LFCU in 2012. The credit union's Jean M. Yokum $5,000 College Scholarship is named for her.