Objectives: The World Health Organization strongly recommends companion of choice for all women during health facility delivery. However, in the developing countries, it is low and not well studied in Ethiopia. Thus, the study aimed to assess the birth attendants’ attitude and practice of companionship during health facility-based childbirth and associated factors in the West Shoa Zone, Ethiopia. Methods: A cross-sectional study design with a concurrent mixed method approach was employed from 17 August to 23 September 2021. A simple random sampling was used to collect data from 422 birth attendants using a pretested structured self-administered questionnaire. The data was entered into Epi-data 3.1 and exported to the Statistical Package for Social Sciences for analysis. Bivariate and multivariate logistic regressions were done. The qualitative data was analyzed manually using thematic analysis, and the result was triangulated with the quantitative data. Results: About, 208 (51.2%) of birth attendants had favorable attitude, and only 79 (19.5%) of them reported that they practice companion presence during childbirth. Reported job satisfaction (adjusted odds ratio = 5.29, 95% confidence interval: 3.08, 9.1), presence of a screen (adjusted odds ratio (AOR) = 3.4, 95% confidence interval: 1.94, 5.99), and wideness of the delivery room (adjusted odds ratio = 4.74, 95% confidence interval: 2.48, 9.04) were factors associated with the attitude of birth attendants. The number of deliveries per month (adjusted odds ratio = 3.34, 95% confidence interval: 1.37, 8.13), having had training (adjusted odds ratio = 3.286, 95% confidence interval: 1.52, 7.08), and presence of a screen (adjusted odds ratio = 2.88, 95% confidence interval: 1.42, 5.85) were statistically associated with practice of companion presence during childbirth. The main themes that emerged as the key barriers to the practice of companion presence during childbirth include structural factors, societal norms and culture, lack of interest, birth attendant-related barriers, unsupportive administration protocol, and companions’ awareness. Conclusion: The magnitude of favorable attitudes and reported practice of birth attendants regarding companion presence during childbirth is low. Structural related factors were the main barriers. Training of birth attendants and structural interventions are needed to ensure that delivery rooms are designed in ways that facilitate the presence of companions during childbirth.