Stems 20-60(-90) cm; base usually reddish, pubescent. Leaves mostly on proximal 1/2 of stem; basal leaves 0-2 at anthesis; cauline leaves 3-10 at anthesis; petiole 0.3-19 cm. Leaf blade round to reniform, 2-8 × 3-14 cm, pubescent; ultimate lobes 5-18, width 4-7 mm (basal), 1-5 mm (cauline), widest at middle or in proximal 1/2. Inflorescences 5-25(-40)-flowered, at least 2 times longer than wide; pedicel 1.5-4(-9) cm, puberulent; bracteoles 2-3 mm from flowers, green, linear, 4-6 mm, puberulent. Flowers: sepals bluish purple to yellowish, (± drab), often partly fading upon drying, puberulent, lateral sepals ± spreading, 8-11 × 3-6 mm, spurs straight, slightly ascending, 9-13 mm; lower petal blades ± covering stamens, 4-6 mm, clefts 0.5-2 mm; hairs well dispersed, mostly near margins and base of cleft, white to yellow or blue. Fruits 10-14(-18) mm, 3.5-4 times longer than wide, pubescent. Seeds wing-margined; seed coat cell surfaces smooth.

Delphinium nuttallii has often been confused with D . menziesii ; it may be distinguished by consistently smaller flowers and usually more flowers per plant than in the latter. Interestingly, each species produces both blue-purple and yellowish flower colors, in separate populations.