Background: Recently, several flavonoids have been shown to have cardioprotective, cancer preventive, or anti-inflammatory properties. However, the specific mechanisms underlying their protective effects remain unclear. Aims: We aimed to investigate the different effects of 3 representative flavonoids—hesperidin, naringin, and resveratrol—on intracellular adhesion molecule-1 (ICAM-1) induction in human umbilical vein endothelial cells (HUVECs) by using high-glucose (HG) concentrations and the possible underlying molecular mechanisms. Methods: In HG-induced HUVEC cultures, the effects of 3 different flavonoids on ICAM-1 production and p38 phosphorylation were examined in the presence or absence of inhibitors targeting the mitogen-activated protein kinase (MAPK) signal transduction pathway. Results: HG stimulation of HUVECs increased the levels of the adhesion molecules ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), and endothelial selectin (E-selectin). Pretreatment with all the 3 flavonoids drastically inhibited ICAM-1 expression in a dose- and time-dependent manner, but did not alter VCAM-1 and E-selectin expressions. Moreover, we investigated the effects of flavonoids on the MAPK signal transduction pathway, because MAPK families are associated with vascular inflammation under stress. These flavonoids did not block HG-induced phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), but completely inhibited the HG-induced phosphorylation of p38 MAPK. SB202190, an inhibitor of p38 MAPK, also inhibited the HG-induced enrichment of ICAM-1. Conculsions: This study demonstrated that hesperidin, naringin, and resveratrol reduced the HG-induced ICAM-1 expression via the p38 MAPK signaling pathway, contributing to the inhibition of monocyte adhesion to endothelial cells.