Purpose This study aimed to determine how an early occupational therapy (OT) intervention affected hospital length of stay (LOS) in a sample of patients with a moderate to severe traumatic brain injury (TBI). Methods This quasi-experimental study was conducted with 2018-2020 data from a rehabilitation center at the King Saud Medical City in Riyadh, Kingdom of Saudi Arabia. The sample of 29 TBI patients included 15 experimental (prospective) group participants who received an early OT intervention and 14 control group (retrospective) participants who did not receive the intervention. The intervention provided patients with daily OT therapy based on their needs and was divided into two phases: the intensive care unit (ICU) phase and the general ward phase. The following measures were used: Glasgow Coma Scale score at admission (both groups), hospital LOS (from admission until discharge; both groups), and functional independence measures (FIM) at admission and discharge (experimental group). Results Experimental group patients had a much shorter LOS (average 61.53 days) compared with the control group (mean 108.86 days). Additionally, the experimental group had a statistically significant increase in FIM scores from admission to discharge. Conclusions These results suggest that providing early OT interventions to patients with moderate and severe TBIs can help decrease their LOS, which can contribute to reduced treatment costs.