Genetic risk factors for Parkinson's disease (PD) remain under-characterized in East Asian populations. We assembled a Taiwanese case-control cohort (2245 PD; 2147 controls), genotyped participants using the Illumina NeuroBooster Array, and imputed 7.6 million variants with the Taiwan Biobank reference panel. Logistic-regression GWAS identified genome-wide significant associations at SNCA and MCCC1, with the lead SNCA signal located in intron 4; conditional and joint analyses suggested an additional 5' SNCA component. We observed suggestive associations at GCH1, PPARGC1A, and GALNT13. Locus-focused haplotype analyses refined the SNCA signal, delineating an East Asian-enriched risk haplotype, and confirmed risk effects of LRRK2 p.G2385R and p.R1628P, including evidence consistent with a gene-dosage effect. A European-derived PRS showed modest discrimination in our cohort (AUC 0.59), while incorporating East Asian and Taiwan-relevant variants improved performance (AUC 0.62). Together, these results define the genetic architecture of PD in Taiwan, highlight shared and population-enriched risk components, and support ancestry-aware PRS construction for improved risk stratification.