Various embodiments, aspects and features of the present invention encompass an expandable pet tunnel system. It is envisioned that embodiments of the solution for an expandable pet tunnel system may have components constructed from any material suitable for a given application, although preferred embodiments may be constructed from kraft paper. Components of an exemplary embodiment may be constructed of a relatively thick paper and reside in either a collapsed state or an expanded state. Pet tunnel components and connector box components may expand “accordion-like” according to a series of gussets or folds in the sidewalls of each component and then connected, one to the next, by aligning entry/exit ports to modularly build a tunnel system.
