In enzymology, a methylmalonyl-CoA carboxytransferase (EC 2.1.3.1) is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are (S)-methylmalonyl-CoA and pyruvate, whereas its two products are propanoyl-CoA and oxaloacetate.

This enzyme belongs to the family of transferases that transfer one-carbon groups, specifically the carboxy- and carbamoyltransferases.

The systematic name of this enzyme class is (S)-methylmalonyl-CoA:pyruvate carboxytransferase.

Other names in common use include transcarboxylase, methylmalonyl coenzyme A carboxyltransferase, methylmalonyl-CoA transcarboxylase, oxalacetic transcarboxylase, methylmalonyl-CoA carboxyltransferase, methylmalonyl-CoA carboxyltransferase, (S)-2-methyl-3-oxopropanoyl-CoA:pyruvate carboxyltransferase, (S)-2-methyl-3-oxopropanoyl-CoA:pyruvate carboxytransferase, and carboxytransferase [incorrect].

As of late 2007, 12 structures have been solved for this class of enzymes, with PDB accession codes 1DCZ, 1DD2, 1ON3, 1ON9, 1RQB, 1RQE, 1RQH, 1RR2, 1S3H, 1U5J, 2D5D, and 2EVB.