Galectin‐10 is involved in the T cell suppressive activity of regulatory T cells and eosinophils alike. We have identified a subpopulation of T cell suppressive eosinophils that express CD16 on the surface and contain more galectin‐10 compared with conventional CD16‐negative eosinophils. Our main goal was to determine how the intracellular protein galectin‐10 is released from eosinophils when exposed to proliferating T cells and if such release could be inhibited. Confocal microscopy and imaging flow cytometry were used to study the release of galectin‐10 from eosinophils incubated with polyclonally activated T cells. T cell proliferation was monitored by measurement of the incorporation of [3H]‐thymidine. Initially, galectin‐10‐containing synapses formed between eosinophils and T cells. Subsequently, the plasma membrane of eosinophils began to disintegrate and cap‐like accumulations of galectin‐10 budded on the eosinophil cell surface. Lastly, eosinophil extracellular traps composed of nuclear DNA and galectin‐10 were freed. It was solely the CD16‐expressing suppressive eosinophils that formed synapses and eosinophil extracellular traps containing galectin‐10. Dissolution of the extracellular traps by DNase I partly abrogated the T cell suppression exerted by eosinophils. Extracellular trap formation has mainly been associated with anti‐bacterial defense, but we show a new putative function of these cellular formations, as mediators of T cell suppression by enabling the release of galectin‐10 from eosinophils.