These moths are important pollinators of deep-throated, night-blooming flowers. The moth extends its long proboscis (a hollow straw-like organ) up to 10 cm into the flower to collect nectar. As the moth removes its proboscis from the flower, pollen grains stick to it and become entrapped on the scales of the moth's body. As it nectars on other plants, it inadvertently deposits this pollen on other flowers and pollinates the plant.

Hawk moths are such good pollinators that some plants have developed distinct pollination syndromes to attract them. One example is the large white petunia (Petunia axillaris), that emits a strong odor during the night to attract hawk moths. Other examples of plants pollinated by the Carolina sphinx moth include Colorado four-o'clock (Mirabilis froebelii), periwinkles (Mandevilla longiflora, Mandevilla petraea), wild tobacco (Nicotiana attenuata), agaves (Agave spp.), and jimsonweed (Datura wrightii). An interesting mutualism has developed between the Carolina sphinx moth and jimsonweed. Larvae are major herbivores of jimsonweed, feasting on the leaves. However, the plant has developed mechanisms to deal with this herbivory - the plant stores resources in its massive roots that can be allocated to new leaf production. In return, the moth is a major pollinator of jimsonweed, whose large white funnel-shaped flowers bloom at night and are filled with nectar. Jimsonweed plants pollinated by the moth have heartier seedlings than those plants that are self-pollinated.

However, the larval stage of this species is considered an agricultural pest. Larvae can defoliate a plant overnight including crop plants like tobacco, tomatoes, potatoes, peppers, and eggplants.