<p>Intratumoral myeloid cells are highly heterogeneous in terms of development and function and are pivotal for forming and regulating the tumor microenvironment. However, the myeloid milieu in triple-negative breast cancer (TNBC) remains poorly understood. Here, to elucidate this myeloid milieu, we integrated in-house and public single-cell RNA sequencing data. We detected diverse neutrophil and mononuclear-phagocyte subtypes and delineated their developmental trajectories and functions. Of particular interest were the <i>VEGFA</i>^<i>hi</i> neutrophil and <i>SPP1</i>^<i>hi</i> macrophage subtypes, which displayed protumoral functions, including angiogenesis. Spatial transcriptomics revealed that they colocalized with epithelial cancer cells and <i>APLN</i>^<i>hi</i> endothelial tip cells in a hypoxic region forming an angiogenic niche. Moreover, patients with <i>SPP1</i>^<i>hi</i> macrophage-enriched TNBC showed poor prognosis, which worsened in patients who also displayed abundant <i>VEGFA</i>^<i>hi</i> neutrophils. These subtypes were also conserved in multiple murine TNBC models. This comprehensive analysis of the myeloid population in TNBC thus reveals a previously undercharacterized interaction between <i>VEGFA</i>^<i>hi</i> neutrophils and <i>SPP1</i>^<i>hi</i> macrophages, elucidating their contributions in the formation of an angiogenic niche.</p>