Developing cellulose-based products is highly important because of their low-cost, reproducibility, and biodegradability. However, extensive application for cellulose has been actually hindered due to its well-known insolubility. Herein, some 22 novel functionalized imidazalium carboxylates exhibit tremendously enhanced dissolution capacity for cellulose even without extra energy consumption and are much superior to the previously reported solvents so far. Systematic investigations reveal that the powerful dissolution capacity for cellulose mainly results from the contribution of the imidazolium skeleton cation, not replacing acidic H atoms in imidazolium skeleton by alkyl, binding more allyl in N atoms of imidazolium cation, and binding an electron-donating group in carboxylate anion. Of particular importance, porous cellulose materials with varying micromorphology, for the first time, are reported by tuning the anionic and/or cationic structures of an IL. Moreover, the regenerated cellulose material retains sufficient thermostability and chemical structure. Therefore, this investigation provides a viable strategy for practical application in cellulose conversion into valuable products even without extra heating.