The subalpine warbler is divided into two distinct subspecies groups, which may possibly be sufficiently diverged to qualify as two separate species (Shirihai et al.

In May 2020, the IOC world bird list recognised the split of western and eastern subalpine warblers into two distinct species.

The eastern subalpine warbler differs from the western subalpine warbler by its deeper blue-grey upperparts, a blackish mask on the lores and ear-coverts, brick reddish-brown coloration confined to the throat and breast and sharply demarcated from a largely white belly, paler flanks and a wider white submoustachial stripe.

It is also frequently found in young cork oak (Quercus suber) forest and in dense but treeless bushy areas.

It uses bushy formations dominated by brambles (Rubus fruticosus) along sunny ravines and valley bottoms and prefers the intermediate stages of post-wildfire succession.