AbstractThe therapeutic effectiveness and biological relevance of technologies based on adherent cells depend on platforms that enable long‐term culture in controlled environments. Liquid‐core capsules have been suggested as semipermeable moieties with spatial homogeneity due to the high mobility of all components in their core. The lack of cell‐adhesive sites in liquid‐core structures often hampers their use as platforms for stem cell‐based technologies for long‐term survival and cell‐directed self‐organization. Here, the one‐step fast formation of robust polymeric capsules formed by interfacial complexation of oppositely charged polyelectrolytes in an all‐aqueous environment, compatible with the simultaneous encapsulation of mesenchymal stem/stromal cells (MSCs) and microcarriers, is described. The adhesion of umbilical cord MSCs to polymeric microcarriers enables their aggregation and culture for more than 21 days in capsules prepared either manually by dropwise addition, or by scalable electrohydrodynamic atomization, generating robust and stable capsules. Cell aggregation and secretion overtime can be tailored by providing cells with static or dynamic (bioreactor) environments.