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Simple Summary: This study explored the effects of age, sex, and muscle type on post-mortem muscle acidification in Botucatu rabbits, addressing the gap between recommended meat quality assessment standards and industry practices. The World Rabbit Science Association (WRSA) suggests chilling carcasses for 24 h at 0–4 °C, while Brazilian practices often involve immediate freezing at temperatures below −18 °C. This study aimed to clarify how these practices affect muscle pH and rigor mortis development. Eighty Botucatu rabbits were categorized into young females and males, does, and bucks. Carcasses were chilled for 24 h at 4 °C. pH and temperature measurements were taken hourly for 24 h post-mortem in the Longissimus lumborum (LL) and Biceps femoris (BF) muscles. Rigor mortis was assessed manually alongside pH measurements. Botucatu does were heavier, with a less marked initial pH drop in the LL and delayed stabilization at 6 h post-mortem. Muscle acidification was more pronounced in the LL than in the BF. Rigor mortis set in at 5 h for young rabbits and bucks, and 6 h for does, resolving by 18 h. Thus, chilling rabbit carcasses for at least 18 h at 4 °C aligns WRSA guidelines with industry needs, ensuring effective rigor mortis and muscle-to-meat transformation. The aim of the present study was to evaluate the characteristics of carcasses, monitor their pH evolution during the first 24 h post-mortem, and determine the time required for the establishment and resolution of rigor mortis in different categories of Botucatu rabbits. Live weight at slaughter, carcass weight, and yield were higher in 12-month-old animals compared to 3-month-old rabbits, regardless of sex. There was an effect of muscle type, age, and sex on the kinetics of muscle acidification, with the Biceps femoris showing a significantly higher pH than the Longissimus lumborum from 4 h post-mortem onward. The establishment of rigor mortis occurred at 5 h post-mortem in young rabbits and bucks and at 6 h post-mortem in does, along with pH stabilization, while the resolution of rigor occurred at 18 h post-mortem for all types of carcasses evaluated. In conclusion, Botucatu rabbit carcasses should be chilled continuously at 4 °C for a minimum of 18 h to ensure efficient rigor mortis progression and muscle-to-meat transformation throughout the carcass. [ABSTRACT FROM AUTHOR]