Particle‐mediated self‐assembly, such as nanocomposites, microstructure formation in materials, and core‐shell coating of biological particles, offers precise control over the properties of biological materials for applications in drug delivery, tissue engineering, and biosensing. We study the assembly of similar‐sized calcium alginate (CAG) and polystyrene sub‐micron particles in an aqueous sodium nitrate solution as a model for particle‐mediated self‐assembly of biological and synthetic mixed particle species. The objective is to reinforce biological matrixes by incorporating synthetic particles to form hybrid particulate networks with tailored properties. By varying the ionic strength of the suspension, we alter the energy barriers for particle attachment to each other and to a glass substrate that results from colloidal surface forces. The particles do not show monotonic adsorption trend to glass with ionic strength. Hence, apart from DLVO theory—van der Waals and electrostatic interactions—we further consider solvation and bridging interactions in our analysis of the particulate adsorption‐coagulation system. CAG particles, which support lower energy barriers to attachment relative to their counterpart polystyrene particles, accumulate as dense aggregates on the glass substrate. Polystyrene particles adsorb simultaneously as detached particles. At high electrolyte concentrations, where electrostatic repulsion is largely screened, the mixture of particles covers most of the glass substrate; the CAG particles form a continuous network throughout the glass substrate with pockets of polystyrene particles. The particulate structure is correlated with the adjustable energy barriers for particle attachment in the suspension.This article is protected by copyright. All rights reserved