Self-healing composites using microvascular channel networks have been intensively studied. Microvascular networks in composite in-plane directions are normally utilized to deliver healing agents to damaged areas. However, this channel configuration is not optimal to form robust networks and to infuse large damaged areas. This study proposes a self-healing system using multiple short microvascular channels in the through-thickness direction. First, the advantage of using this channel configuration was confirmed through delamination filling tests. Next, the feasibility of this channel configuration was evaluated by tensile tests and four-point bending tests. Double cantilever beam tests were then conducted to confirm its healing function. Finally, this system was applied to composite stiffened panels and the healing performance was evaluated using compression testing following panel indentation. The healing system almost fully recovered the original strength, confirming its high potential under practical conditions. Additionally, the weight reduction potential of the self-healing system was discussed through a strength comparison of specimens with different thicknesses.