The aim of the current work was to study natural radioactivity in soil and the correlation between ²²²Rn and ²²⁶Ra in the ground and to assess the onsite and indoor long-term excess cancer risk at the bauxite bearing area of Fongo-Tongo in Western Cameroon. ²²²Rn was measured in the ground at a depth of one meter, using Markus 10 detector. ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations were measured in soil by two techniques, in situ and laboratory gamma spectrometry. The mean values of ²²²Rn concentrations in the ground were 69 ± 18 kBqm⁻³ for Fongo-Tongo and 82 ± 34 kBq m⁻³ for the locality of Dschang, respectively. The mean values of ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations obtained with in situ gamma spectrometry were 129 ± 22, 205 ± 61, and 224 ± 39 Bq kg⁻¹ for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively, and those obtained by laboratory gamma spectrometry were 129 ± 23, 184 ± 54, and 237 ± 44 Bq kg⁻¹, respectively. A strong correlation between ²²²Rn and ²²⁶Ra activity concentrations determined by in situ and laboratory measurements (R² = 0.86 and 0.88, respectively) was found. In addition, it is shown that the total excess cancer risk has a maximum value of 8.6 × 10⁻³ at T = 0 year and decreases progressively in the long term. It is also shown that ²²⁶Ra makes a major contribution, i.e., above 70%, to the total excess cancer risk.