Solieria tenuis has the tendency to become a potential bloom in some regions of the sea in China. It has massive biomass. Therefore, making the best use of the bioresource of S. tenuis has gained attention. This study proposed a process for the comprehensive extraction of carrageenan and phycoerythrin from new resource S. tenuis and measured their bioactivities. The results showed that the purity of phycoerythrin could be up to 4.19 and the yield of phycoerythrin could be 0.06 mg/g (dry weight). The yield of carrageenan was 19.60% at 4% alkali concentration, 2 h alkali treatment time, and 62 °C alkali treatment temperature using the S. tenuis residue. The phycoerythrin had applications as an antioxidant and antibacterial agent, and carrageenan had applications in the culture medium. Thus, this emerging method fully used S. tenuis as new bioresources, which realized high value use and reduced the nitrogen content in production, having potential applications in the future.Graphical Abstract: