The aim of this study was to evaluate the effects of lactic acid and glyceryl lactate on growth performance, antioxidant capacity, and intestinal health in piglets. This study included 240 castrated male piglets (initial body weight: 7.50 ± 0.54 kg) assigned to four groups: CON (basal diet), LA (basal diet + 0.5% lactic acid), GL (basal diet + 0.5% glyceryl lactate), and LG (basal diet + 0.5% lactic acid + 0.5% glyceryl lactate). Each group had six replicates of 10 piglets. The trial lasted 28 days. Compared with the control group, the GL and LG groups showed enhanced growth performance and reduced diarrhea rates in piglets. The LA and LG groups showed decreased intestinal chyme pH and increased digestive enzyme activities. Moreover, the GL and LG groups displayed elevated jejunal mRNA levels of the tight junction protein occludin and mucin MUC2, enhanced expression levels of Nrf2 signaling pathway genes, increased activities of the antioxidant enzymes GPX and CAT, and reduced MDA content. Acidifier supplementation also modulated cecal bacterial abundance and short-chain fatty acid (SCFA) content. Genera such as Faecalibaculum, Nocardiopsis, Collinsella, CAG269, Allobaculum, and Enterococcus were affected. In conclusion, glyceryl lactate and its combination with lactic acid improved piglet growth performance by enhancing intestinal barrier function, antioxidant capacity, microbial community structure, and SCFA production.