Diaporthosporella cercidicola, collected from diseased branches of Cercis chinensis in China, is herein described and illustrated. Evidence for this new genus and species is provided by both holomorphic morphology and phylogenetic analysis. Diaporthosporella cannot be classified into any existing family. Thus, Diaporthosporellaceae is introduced as a new family to accommodate Diaporthosporella, typified by D. cercidicola. Morphologically, Diaporthosporellaceae can be distinguished from other diaporthalean families by irregularly uniseriate, allantoid or subreniform ascospores, conidiophores acropleurogenous, branched or sympodially branched, cylindrical, aseptate, and ellipsoidal, biguttulate conidia. Phylogenetic analysis using the internal transcribed spacers (ITS) and large subunit (LSU) ribosomal (r) DNA sequence data shows that Diaporthosporellaceae forms a distinct family within Diaporthales.