The English name and the specific humei commemorate Allan Octavian Hume, a British civil servant and ornithologist based in India.

With its long supercilium, crown stripe and yellow-margined tertial remiges, it is very similar to the yellow-browed warbler (P. inornatus).

It occurs from the Hindu Kush and Karakoram east and north to the Tien Shan in China and the Altay Mountains in Mongolia.

[5] Particularly on autumn migration, this tiny warbler is prone to vagrancy as far as western Europe, despite a 3,000 km distance from its breeding grounds.

Non-breeding adults may stray around a lot in summer, when Mandell's leaf warblers are fairly common summer visitors to subtropical and temperate montane humid forests of Bhutan, around 2,000-3,500 m ASL and dominated by Bhutan fir (Abies densa) or by Himalayan hemlock (Tsuga dumosa) and rhododendrons, though the subspecies is not a regular breeder in that country.

[7] It was recently split from the yellow-browed warbler (Phylloscopus inornatus), based on differences in morphology, bioacoustics, and molecular characters.