This tree grows 10–25 m (33–82 ft) tall, with large heart-shaped to five-lobed leaves 15–40 cm (6–16 in) across, arranged in opposite pairs on the stem. On young growth, the leaves may be in whorls of three and be much bigger than the leaves on more mature growth. The leaves can be mistaken for those of the catalpa.

The very fragrant flowers, large and violet-blue in colour are produced before the leaves in early spring, on panicles 10–30 centimetres (4–12 in) long, with a tubular purple corolla 4–6 centimetres (1+1⁄2–2+1⁄4 in) long resembling a foxglove flower. The fruit is a dry egg-shaped capsule 3–4 centimetres (1+1⁄8–1+5⁄8 in) long, containing numerous tiny seeds. The seeds are winged and disperse by wind and water. Pollarded trees do not produce flowers, as these form only on mature wood.

Paulownia tomentosa requires full sun for proper growth. It is tolerant of pollution and can tolerate many soil types. It can also grow from small cracks in pavements and walls. Paulownia can survive wildfires because the roots can regenerate new, very fast-growing stems.