Dicyphus agilis Uhler (Hemiptera: Miridae) is reported for the first time in Colombia, and it is associated with Sparmannia africana L. (Malvales: Malvaceae) and in urban and Nicotiana tabacum L. (Solanales: Solanaceae) in rural areas as a predator of aphids. This study describes the external structure, genitalia, and morphometry of the most prominent structures of males and females of D. agilis. Adults of this insect were collected from tobacco fields at Municipality of San Gil, Santander, Colombia. Morphological characteristics of D. agilis were: body oblong-elongated, small head, reniform compound eyes, rostrum and antennae with four segments, thorax punctate, femur with six dark spots, elongated tibia, tarsus with two tarsomeres; male genitalia with phallus and females with ovipositor invaginated. Morphometric data indicated that D. agilis is 3–5 mm in length with evident sexual dimorphism, with females being larger than males in all structures except the antennae. The morphological features of D. agilis are necessary to differentiate this species from other Mirid species with phytophagous habits in agricultural crops and to establish biological control programs in Colombia.