Hypertension and its connection to high salt consumption have been observed in the Thai population. This study mainly contributed to the literature to examine the dietary-salt-related determinants associated with the risk of hypertension in rural northern Thailand, which exhibited the highest prevalence of hypertension. A total of 376 adults residing in San Pa Tong District, Chiang Mai province, were face-to-face interviewed using a structured questionnaire assessing dietary-salt-related knowledge, attitudes, consumption, sources, and habits. The subject’s blood pressure (BP) was measured twice before and after the interview. Hypertension was defined as a systolic BP ≥ 130 mmHg or a diastolic BP ≥ 80 mmHg. The dietary-salt-related knowledge, attitude, and habits toward salt reduction were positively correlated; however, knowledge and attitudes were not significantly correlated with consumption. Multivariate logistic regression results indicated subjects who frequently bought ready-to-eat food, ate out, or used bouillon cube/monosodium glutamate (MSG) during food preparation were likely to have hypertension (OR = 2.24, 95% CI: 1.36–3.69, p = 0.002). MSG was heavily consumed and used as a flavor enhancer in northern Thai cuisine; however, a few subjects realized it contains sodium due to no salty taste. The deficiency of specific dietary-salt-related knowledge illustrated the need for tailored educational intervention strategies.