The potential of the mirid predator Dicyphus hesperus Knight (Heteroptera: Miridae) as a biological control agent of the sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and the potato psyllid, Bactericera cockerelli Sulcer (Hemiptera: Psyllidae) in tomato was investigated in two experiments. The first experiment focused on the study of the life history traits of D. hesperus when fed on nymphs of the potato psyllid compared with the factitious prey Ephestia kuehniella Zeller (Lepidoptera: Pyrallidae) eggs. Although reproductive and development rates were higher on E. kuehniella eggs, the predator exhibited a good intrinsic rate of natural increase (rm) when feeding on B. cockerelli nymphs (rm: B. cockerelli 0.069 ± 0.0001; E. kuehniella 0.078 ± 0.0001), thus reflecting good potential as a biocontrol agent of this pest. The second experiment focused on the efficacy of D. hesperus as a biocontrol agent of the potato psyllid and the sweetpotato whitefly in a tomato greenhouse. Prey species were offered individually or together in a series of five treatments in greenhouse cages. Results showed that the predator was able to establish and suppress populations of both pests inhabiting tomato plants when pests occurred alone or together. Thus, D. hesperus was demonstrated to be a suitable biocontrol agent of these two important pests that could be used in tomato greenhouses.