Background: Angiogenesis is essential for tissue development, and therefore its dysregulation can cause various diseases, including cerebrovascular disease. Galectin-1, encoded by the lectin galactoside-binding soluble-1 gene (LGALS1), has critical roles in the regulation of angiogenesis, but the underlying mechanisms need further clarification. Methods: LGALS1 was silenced in human umbilical vein endothelial cells (HUVECs) and whole transcriptome sequencing (RNA-seq) was then performed to investigate potential targets for galectin-1. Galectin-1-interacting RNA data was also integrated to explore how galectin-1 might regulate gene expression and alternative splicing (AS). Results: A total of 1451 differentially expressed genes (DEGs) were found to be regulated by silencing LGALS1 (siLGALS1), comprising 604 up- and 847 down-regulated DEGs. Down-regulated DEGs were primarily enriched in angiogenesis and inflammatory response pathways, and included CCL2, GJA5, CALCRL, ACKR3, HEY1, AQP1, CD34, ECM1, RAMP2, and SELP. These were validated by reverse transcription and quantitative polymerase chain reaction (RT-qPCR) experiments. siLGALS1 was also used to analyze dysregulated AS profiles, such as the promotion of exon skipping (ES) and intron retention, and inhibition of cassette exon events. Interestingly, regulated AS genes (RASGs) were found to be enriched in focal adhesion and in the angiogenesis-associated vascular endothelial growth factor (VEGF) signaling pathway. Furthermore, based on our previously published RNA interactome data for galectin-1, hundreds of RASGs were found to be bound by galectin-1, including those enriched in the angiogenesis pathway. Conclusions: Our results demonstrate that galectin-1 can regulate angiogenesis-related genes at transcriptional and post-transcriptional levels, probably by binding to the transcripts. These findings expand our understanding of the functions of galectin-1 and the molecular mechanisms that underlie angiogenesis. They also indicate that galectin-1 could serve as a therapeutic target for future anti-angiogenic treatments.