Clive Cussler married Barbara Knight in 1955 and they remained married for nearly 50 years until her death in 2003. Together they had three children, Teri, Dirk and Dana who have given him four grandchildren.
After his discharge from the military Cussler went to work in the advertising industry, first as a copywriter and later as a creative director for two of the nation's most successful advertising agencies. As part of his duties Cussler produced radio and television commercials, many of which won international awards including an award at the Cannes Lions International Advertising Festival.