Helichrysum molestum is a perennial herb up to 1 m tall, producing several stems that are simple below and branching into compound inflorescences. Branches are stout and sticky with numerous tiny glands. The uppermost parts are cobwebby and closely leafy. Leaves are mostly 65-100 x 18-32 mm, smaller on the inflorescence branches, oblong or oblong-ovate, the tip acute with a sharp point and the base clasping the stems. Both leaf surfaces are glandular and sticky.

Flower heads are large and somewhat flattened, ± 11-14 mm long, 20-30 mm across the radiating bracts. Many flower heads are borne in an open, branched inflorescence. Bracts are much longer than the florets, glossy, bright yellow and radiating. Pappus bristles are many and the same length as the florets. It flowers mainly in March and April.

Helichrysum molestum can be easily be confused with H. difficile, but is usually more robust, with larger leaves; it is distinguished from H. cooperi by its perennial habit and larger heads.