Tetrasubstituted　olefins　as　a　pivotal　scaffold　have　been　extensively　employed　in　pharmaceuticals,　natural　products,　polymer　chemistry,　and　material　sciences　and　arouse　great　attention　in　chemical　community.　Despite　advances　on　the　assembly　of　fully　carbon　tetrasubstituted　olefins,　the　synthesis　of　tetrasubstituted　alkenyl　monohalides　are　underdeveloped　and　elusive.　Herein,　we　report　four　intriguing　migration　reactions　from　alkynyl　tetracoordinate　boron　species,　in　which　various　common,　inexpensive,　and　user-friendly　halogen　electrophiles　(Selectfluoro,　TCCA,　NIS,　and　NBS)　are　suitable　electrophilic　halogen　sources.　Versatile　tetrasubstituted　olefins　were　thus　readily　accessible　from　transition-metal-catalyzed　transformations　of　these　newly　built　tetrasubstituted　alkenyl　monohalides　under　suitable　reaction　conditions.　The　mechanistic　investigations　suggest　that　different　electrophilic　halogen　sources　promote　different　aryl　migration　routes　of　alkynyl　tetracoordinate　boron　species,　rendering　various　tetrasubstituted　alkenyl　monohalides,　respectively.　Distinct　reaction　modes,　unusual　mechanism,　valuable　products,　and　versatile　transformations　portray　the　advantages　and　significance　of　our　protocol.　©　2023　Elsevier　Inc.