Carrot is a root vegetable crop. The management of agronomic practices is an important factor that strongly affects the growth, yield and quality of carrots. A field experiment was conducted to evaluate the growth, yield and quality of carrots affected by different types of organic manure and mulching materials in Diguna Fango Woreda, South Ethiopia. The study consisted of four organic manures (control, 20 t PM ha − 1 , 20 t FYM ha− 1 and 20 t mixed manure (10 t PM + 10 t FYM) ha− 1 and three types of mulching (no mulching, sawdust mulching and grass mulching) laid in the RCBD, with four replications in a factorial arrangement. Analysis was performed using the SAS software package. Root diameter, root fresh weight, root dry weight, marketable yield and total root yield were significantly (P ≤ 0.05) affected by the interaction effect of organic manure and mulching materials. The main effects of organic manure and mulching also significantly (p ≤ 0.05) affected plant height, leaf number, leaf length, root length, unmarketable root yield, root dry matter content, forked roots, cracked roots and TSS. Among the different combinations, 20 t of mixed manure (10 t PM + 10 t FYM) with grass mulching ha− 1 surpassed all the other combinations in terms of maximum root length (22.45 cm), root diameter (6.60 cm), root fresh weight (179.25 g), root dry weight (26.16 g), marketable root yield (27.90 t ha− 1) and total root yield (33.92 t ha− 1) during the experimental year. Similarly, PM with grass mulching also produced better results pertaining to carrot growth and yield. Based on these results, the highest net benefit (360,520 Birr ha− 1) with an MRR of 3803% was obtained from the treatment combination of 20 t FYM with grass mulching. Therefore, the use of 20 t FYM with grass mulching could be recommended for carrot production in the study area. Since this study is limited to the use of organic manure with mulching materials during one season and at one location, the results should be repeated across seasons and locations.