Background: Life balance is defined as “a satisfying pattern of daily activity that is healthful, meaningful, and sustainable to an individual within the context of his or her current life circumstances”. To assess life balance, the self-report instrument Life Balance Inventory (LBI) has been developed in the US. The aim of this study was to evaluate cross-cultural, construct validity and test-retest reliability of translated versions of the LBI in people with multiple sclerosis (MS) within different European cultures (Dutch, Flemish, Slovenian, and Spanish). Method: The LBI was translated according to the principles of forward/backward translation and the cultural adaption process of patient-reported outcomes and evaluated in people with MS in each country/language area. LBI (score range 1–3; higher scores refer to better balance) was registered twice with an interval of 7 days to evaluate test-retest reliability using Intraclass Correlation Coefficients (ICCs) and Bland Altman analyses. To evaluate construct validity, Pearson correlations of the LBI with quality of life, fatigue, depression and self-efficacy were explored. Results: The total sample (n = 313, 50 ± 11 years of age, MS duration 13 ± 8 years) consisted of five subsamples: Dutch (n = 81, 74% women, 54 ± 9.6 years of age), Flemish 1 (n = 42, 57% women, 49 ± 12 years), Flemish 2 (n = 105, 63% women, 50 ± 10.6 years), Slovenian (n = 48, 79% women, 44 ± 11.2 years) and Spanish (n = 37, 62% women, 47 ± 9.0 years). Baseline total LBI scores differed between subsamples (F(4, 312)=7.19, p < 0.001). ICC [95% CI] of total LBI was 0.88 [0.83–0.92] (Flemish 2), 0.65 [0.39–0.82] (Flemish 1), 0.55 [0.37–0.69] (Dutch), 0.45 [0.15–0.67] (Spanish) and 0.35 [0.07–0.59] (Slovenian). Systematic error was present in one sample; no proportional bias occurred. Correlations ranged from 0.05 to 0.55 for quality of life and self-efficacy, from −0.50 to 0.05 for fatigue and from −0.44 to −0.28 for depression, not fully supporting the hypotheses. Conclusion: The study results provide limited support for test-retest reliability, cross-cultural and construct validity of the LBI in different European subsamples. Although LBI may serve as a supportive tool in goalsetting in rehabilitation, the current version of LBI is not recommended for (international) research purposes.