The development of form-stable phase-change materials (FSPCMs) with large latent heat, excellent thermal stability, and recyclability is essential for their practical applications in thermal or solar energy saving. In this paper, we first report the FSPCM composites with exceptional latent heat by employment of sugar alcohol, in this case erythritol (Ery) and mannitol (Man), as organic phase-change materials (PCMs) and carbonized kapok fiber (KKf) with a high Brunauer-Emmett-Teller surface area of up to 3396 m2 g-1 as porous supporting materials. The unique hollow tubelike structure of KKf makes it possible to load the organic PCMs inside and outside the KKf tubes, and a high load value of 93% was achieved. The carbonized KKf could not only endow itself robust thermal stability but also significantly decrease supercooling while enhancing the thermal conductivity of the PCM composites by over 130% compared with pure Ery and Man. Compared with these reported PCM composites for low and medium temperature usually having latent heat ranges from 150 to 258 J g-1, our PCM composites display exceptionally high latent heat ranging from 297 to 350 J g-1, owing to the inherent large latent heat of sugar alcohols. Notably, as a kind of natural plant fiber with abundant availability, the employment of kapok fiber as the supporting material via physical incorporation with sugar alcohols thus makes the approach simple, green, and cost-effective, which is of great technological significance for their real energy-saving applications owing to their high energy storage performance, high loading values, and enhanced thermal conductivity.