A liquid diet for rearing Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) was developed. Several yeast-based products were evaluated as diet ingredients, and a combination of whole cell yeast (LBI2240) and hydrolyzed yeast (such as FNILS65) in 1:1–3:1 ratio was selected for use in the study. Larvae reared in a liquid diet with LBI2240:FNILS65 ratios of either 1:1 or 3:1 resulted in the same pupal recovery as to those reared in the conventional mill fee- based control diet. Larvae reared in a liquid diet with whole cell yeast only yielded the lowest pupal production, whereas other parameters such as adult emergence, adult fliers, pupal weight, egg production, and percentage of egg hatch were not affected. In diets fortified with vitamin-fortified yeast (RDA) or glutamine-rich yeast (GSH), there was no enhanced effect on insects, whereas some detrimental effects were observed in some of the parameters measured. A whole cell yeast to hydrolyzed yeast ratio of 3:1 was found to be the most suitable based on quality control parameters measured and cost-effectiveness. This is recommended for use in liquid diets targeting C. capitata mass rearing because the cost of whole cell yeast was 5 times cheaper than that of hydrolyzed yeast. This study also demonstrates that it is possible to rear C. capitata in a liquid diet at a similar cost to mill feed diet and still maintain the same fly quality as that from the conventional control diet.