Cow’s performance and herd management strategies such as productivity and herd structure influence dairy enteric CH₄ emission and profitability. This study aims to quantify the effects of culling rate (CUR) milk production improvement (MPI, a proxy for genetic and management progress), and the interaction between them on enteric CH₄ emission and farm profitability. Hence, a monthly Markov Chain herd structure model was built and used to simulate the herd for 15 calving intervals (CI, with 13-mo length). Enteric CH₄ emission and farm profit (milk income over feed cost minus transaction cost) were calculated as the average for one CI. The model was used to study CUR from 25% to 45% with 5% intervals and annual MPI of 1%, 1.5%, and 2%. Every tested scenario started at a herd’s steady state. Daily milk production in 35% CUR herds (27.36 kg per cow per d) was slightly higher than herds with other CUR levels. Herds with 45% CUR had the lowest daily milk production, followed by 25%, 40%, and 30% CUR herds. Higher CUR herds (30–45%) with 1.5% or 2% MPI started to have higher productivity (milk per cow per d) than 25% CUR with the same MPI during the 4th CI due to faster milk production increase. Overall, the lowest emission occurred when 25% CUR + 2% MPI herds and the highest when 45% CUR + 1% MPI herds. With the same MPI, higher CUR herds always had higher emission per kg of FCM. Farm profit was $5.55/cow per d for 25% CUR and $5.50/cow per d for 45% CUR at the beginning. At the end, herds with 25% CR + 2% MPI had the highest profit ($) and herds with 45% CR + 1% MPI had the lowest profit ($). With the same CUR, higher MPI always led to a higher farm profit. With the same MPI, lower CUR led to a higher farm profit. This study confirmed that MPI was the ultimate approach to reduce enteric CH₄ emission and higher CUR leads to higher enteric CH₄ emission per unit of milk with the same MPI. Milk production improvement had a greater impact on enteric CH₄ emission and profitability than CUR.