Campanula uniflora is a small perennial herb of dry tundra and grassy places in the mountains with a narrow funnel-like blue flower. Plants are decumbent to erect, reaching 5-25 tall, with a single to few stems arising from a stout caudex. Stems are glabrous. Leaves are primarily attached to the stem, alternately arranged, dark green, almost leathery, glabrous, margins entire. Lower leaves tend to be petiolate, elliptic, oblong to spatulate while upper leaves are sessile, linear to lanceolate. Flowers are solitary, slightly nodding, perfect, the petals fused into a narrow blue corolla, 7-11 mm long with ovate lobes as long as the tube. The calyx lobes are lance-attenuate with white pubescence and almost as long as the corolla but without the narrow teeth of C. lasiocarpa. Campanula uniflora could be confused with the more common species of harebell in the park, Campanula lasiocarpa which has dentate leaves, and toothedsepals, and a larger, bell-shaped corolla much longer than the calyx.
Campanula uniflora usually flowers in mid to late summer (July-early August).
Campanula uniflora is monoecious with bisexual flowers. Flowers in the genus Campanula are typically protandrous, the anthers releasing pollen before the stigmas are receptive. Pollen is shed onto the style. If insects visit with pollen from other flowers, cross-fertilization can occur; if not, leftover pollen will self-fertilize the flowers. C. uniflora in Iceland and Greenland are predominately self-fertilizing (Ægisdóttir and Thórhallsdóttir 2006). Seeds are wind dispersed.
Campanula uniflora is an incompletely circumpolar species with an arctic-alpine distribution, occurring in arctic regions of North America, Europe and just reaching into the Russian Far East in Asia. In North America, there are disjunct populations south to Quebec, Alberta, British Columbia and the Rocky Mountain states. In Alaska, Campanula uniflora occurs from the Alaska Range north and in the Aleutians and Bering Sea Islands. This species occurs sporadically in suitable habitat in Denali, occurring most frequently in the mountains in the northeastern quadrant of the Park, but with stations on both sides of the Alaska Range crest.