On-demand single-photon sources operating at telecom wavelengths are crucial for quantum communication and photonic quantum technologies. In this work, we demonstrate high-purity, indistinguishable single-photon generation in the telecom O-band from an InAsP/ InP nanowire quantum dot. We measured a single-photon purity of g²ð0Þ ¼ 0:006 6 0:003 under above-band excitation. Furthermore, we characterize two-photon interference via Hong–Ou–Mandel measurements and achieve a photon indistinguishability of 81:1% 6 3:7% with a temporal postselection of a 300 ps time window and 5:6% 6 1:5% without temporal postselection. We estimate a first-lens source efficiency of ～28%. These results highlight the potential of nanowire quantum dots as a promising source of telecom single photons for photonic quantum applications, offering deterministic positioning, efficient photon extraction, and scalable production.