Objective To investigate the efficiency and mechanism of C1q tumor necrosis factor-related protein 3 (CTRP3) on reprogramming of cardiac fibroblasts (CFs) into induced cardiomyocyte-like cells (iCMs) by Sendai virus (SeV) vector overexpressing Gata4, Mef2c and Tbx5 (SeVGMT). Methods CFs were divided into Control, NC-Lv, CTRP3-Lv, NC-sh, and CTRP3-sh groups. NC-Lv, CTRP3-Lv, NC-sh, and CTRP3-sh were transfected into CFs using Lipofectamine 3000 reagent for 48 hours. Lipofectamine 3000 reagent was then mixed with SeVGMT and incubated at room temperature for 48 hours, the culture medium was then replaced, and cells were cultured for 21 days. Cell morphology was observed under a microscope at 0, 3, 7, 14, and 21 days. Expression levels of the myocardial-specific proteins α-myosin heavy chain (α-MHC), α-actin, cardiac troponin T (cTnT), connexin 43 (Cx43), cardiac muscle α-actin (Actc1), and myosin heavy chain 6 (Myh6) were detected at different time points by immunofluorescence, quantitative reverse transcription-polymerase chain reaction, and Western blot, and the proportions of beating cells at different time points were calculated. Results The relative fluorescence intensity and mRNA and protein levels of α-MHC, α-actin, cTnT, Cx43, Actc1, and Myh6 in CFs in each group increased with increasing culture time (P<0.05), with significantly higher expression levels of myocardial-specific proteins at 14 days of culture than at 7 days (P<0.05). The relative fluorescence intensities and mRNA and protein levels of α-MHC, α-actin, cTnT, Cx43, Actc1, and Myh6 in CFs at 3, 7, 14, and 21 days of culture were significantly increased in the CTRP3-Lv group compared with the NC-Lv group (P<0.05), but were significantly decreased in CFs in the CTRP3-sh group compared with the NC-sh group (P<0.05). Beating cells appeared in CFs in each group at 7 days of culture. The proportion of beating cells in each group increased with increasing culture time (P<0.05), and the proportion was significantly higher at 14 days than at 7 days (P<0.05). The proportion of beating cells among CFs was increased in the CTRP3-Lv group at 7, 14, and 21 days of culture compared with the NC-Lv group (P<0.05), while the proportion of beating cells in the CTRP3-sh group was decreased compared with the NC-sh group (P<0.05). Conclusions CTRP3 can enhance SeVGMT reprogramming of CFs into iCMs.