Background: Suicide is a global issue among the elderly. The number of older people committing suicide is proliferating, and the elderly suicide rate is the highest among all age groups in China. The possible protective factors against suicidal ideation should be investigated for prevention and intervention efforts. The objectives of the present study are as follows: (1) to examine the psychometric properties of the three-dimensional inventory of character strengths (TICS) with a sample of older adults; (2) to investigate correlations among suicide ideation, wellbeing, and character strengths; and (3) to explore the possible protective roles of the three character strengths and wellbeing in explaining suicidal ideation among older adults. Methods: A cross-sectional study comprising 308 older adults aged at least 50 years old from nursing homes was conducted. Four questionnaires, namely, the TICS, the Geriatric Suicide Ideation Scale—10 items, the Brief Inventory of Thriving, and the Satisfaction with Life Scale, were used. Exploratory structural equation modeling, intraclass correlation coefficients, partial correlations, and sets of hierarchical regressions were adopted to estimate and report the results. Results: TICS could be used to assess the character strengths (i.e., caring, inquisitiveness, and self-control) among older adults with an acceptable goodness-of-fit (chi square = 157.30, df = 63, p < 0.001, CFI = 0.94, TLI = 0.90, RMSEA = 0.07, 90% CI = [0.06, 0.08]). Wellbeing (life satisfaction: B = −0.14, t = −2.55, p = 0.01; thriving: B = −0.52, t = −9.64, p < 0.001) and character strengths (caring: B = −0.45, t = −11.84, p < 0.001; inquisitiveness: B = −0.33, t = −7.89, p < 0.001; self-control: B = −0.45, t = − 10.83, p < 0.001) have exhibited a significant association with suicidal ideation among older adults. Moreover, character strengths have shown an independently cross-sectional relationship with suicidal ideation, explaining 65.2% of the variance of suicidal ideation after controlling for the wellbeing and demographics. Conclusion: This study indicated that character strengths were associated with low levels of suicidal ideation. Therefore, the protective factors against suicidal ideation among older adults should be given additional attention.