Soybean ( Glycine max [L.] Merr.) has been grown in diverse environments in a wide range of latitudes in the world. However, the adaptation of soybean to low-latitude, high-altitude environments characterized by short day and low temperature is still in its early stages. To understand the genetic basis of adaptation in this region, we conducted cultivar screening in low-latitude, high-altitude mountainous regions and carried out genome-wide association studies (GWAS) using 200 diverse soybean cultivars spanning maturity groups 000 to VIII. Evaluation of flowering time (DTF), maturity time (DTM), and other agronomic traits including node number on main stem (NNM), plant height (PH), effective number of pods per plant (EPN) and 100-seed weight (HGW) were performed in Bamei with the altitude of 3460 m (30°29’4”N and 101°28’50”E) and Xianshui with the altitude of 2946 m (30°57’48”N and 101°9’26”E), in Daofu county, Sichuan province, southwest China, in 2019 and 2023, respectively. We screened 5 MG I-II adapted cultivars for Bamei and 17 MG II-V cultivars, for Xianshui, exhibiting late flowering and maturity, along with tall plant height, and high number of nodes and pods per plant. The allelic combinations E1/e2-ns/e3-tr/E4 and E1/e2-ns/E3/E4, and only E1/e2-ns/E3/E4 predominated in the adaptive cultivars in Bamei and Xianshui, respectively. Thus, the cultivars adaptive to low-latitude and high-altitude regions are featured with relatively late flowering and maturing in MG I-V mostly from mid- and low-latitude region with allelic combination mostly of E1/e2-ns/E3/E4. Additionally, our results revealed 9, 6, and 2 genomic regions significantly associated with DTF, NNM and PH, respectively, with two of these genomic regions having QTNs significantly associated with both DTF and PH. Most significant QTNs of the genomic regions associated with DTF were located near previously identified quantitative trait loci, and their alternative loci caused significant differences in flowering time. Furthermore, 7 genomic regions were located near homologs of Arabidopsis flowering time genes FD-1, bZIP29, SEC, PA2, PIE1, FY, IAA31, AS1 and MBD9. Non-synonymous mutations within the candidate genes Glyma.09g112200 ( GmPIE1) , Glyma.13g198200 ( GmFY) and Glyma.17g042800 ( GmIAA31) were found to cause later flowering and taller plant height in both environments. Collection of adaptive cultivars, molecular markers, and candidate genes identified in this study holds substantial promise within the realm of soybean adaptation in low-latitude and high-altitude regions.