Background: β3-AR is an important factor involved in the activation of ERK protein signaling cascade, which can positively contribute to the regulation of adipose tissue metabolism and its conversion into brown adipose tissue. Diabetes mellitus can lead to dysfunction of these factors. Objectives: The current study aimed to investigate the effect of swimming training combined with cinnamon consumption on β3-AR and ERK2 gene expression in the visceral adipose tissue from diabetic rats. Methods: In this experimental-fundamental study, 35 male Wistar rats (mean weight: 200 ± 20 g) were selected and randomly assigned into four groups after the induction of diabetes by streptozotocin. These groups included: (1) healthy control, (2) control, (3) swimming, (4) cinnamon, and (5) swimming cinnamon (n = 7 in each group). The training groups were put through a five-days-a-week workout for four weeks according to the training protocol. Gene expression levels were measured by in vitro real-time PCR. The collected data were analyzed using one-way ANOVA and Tukey’s post hoc test. Results: The expression levels of β3-AR and ERK2 protein genes in the visceral adipose tissue of diabetic rats (P = 0.0001) were significantly affected by swimming training and cinnamon consumption. Conclusions: It was shown that cinnamon supplementation may have increased β3-AR levels, which was more effective than training, while training had a greater effect on ERK2 levels and increased them. Therefore, it was concluded that cinnamon consumption combined with training may have greatly contributed to the conversion of white adipose into brown adipose tissues.