Thompson specialised in portraiture that combined American realism with Italian Romanticism. His work on William Cranch Bond and Belinda Lull Randall shows a focus on clear lighting and smooth skin tones. He often painted religious or allegorical subjects like Angel and Young Woman. These pieces moved away from the documentary nature of early American art. He used a soft colour palette to create a sense of calm in his sitters.

Modern collectors value Thompson for his ability to capture individual personality without excessive ornamentation. His portraits possess a quiet dignity that fits well in contemporary interiors. Works such as Mother and Child with Attendant offer a glimpse into nineteenth-century domestic life. The clean lines and balanced compositions of his paintings remain visually effective today. His art provides a link to the era when American artists first began to look toward Europe for technical refinement.