A series of styrylquinolines was designed and synthesized based on the four main quinoline scaffolds including oxine, chloroxine and quinolines substituted with a hydroxyl group or chlorine atom at the C4 position. All of the compounds were tested for their anticancer activity on wild-type colon cancer cells (HCT 116) and those with a p53 deletion. Analysis of SAR revealed the importance of electron-withdrawing substituents in the styryl part and chelating properties in the quinoline ring. The compounds that were more active were also tested on a panel of four cancer cell lines with mutations in TP53 tumor suppressor gene. The results suggest that styrylquinolines induce cell cycle arrest and activate a p53-independent apoptosis. The apparent mechanism of action was studied for the most promising compounds, which produced reactive oxygen species and changed the cellular redox balance.