This　study　comprehensively　investigated　the　mechanical　behavior　of　shield　tunnel　segmental　joints　strengthened　with　prestressed　carbon　fiber-reinforced　polymer　(CFRP)　plates　through　both　experimental　and　numerical　approaches.　Experimental　tests　were　conducted　on　unstrengthened　(SJ-0)　and　strengthened　(SJ-1)　segmental　joint　specimens　to　explore　their　ultimate　bearing　capacity　and　assess　the　effectiveness　of　the　strengthening.　The　results　indicated　significant　improvements　in　stiffness　and　load-bearing　capacity　due　to　the　prestressed　CFRP　plate　strengthening.　Notably,　compared　to　the　unstrengthened　specimen,　the　strengthened　specimen　exhibited　a　69　%　reduction　in　rotational　angle　and　a　substantial　25　%　to　49.6　%　decrease　in　mid-span　deflection　under　identical　load　conditions.　Additionally,　crack　formation　was　effectively　decreased,　and　overall　horizontal　and　vertical　displacements　were　significantly　reduced,　as　quantified　using　digital　image　correlation　technology.　A　finite-element　model　was　developed　to　validate　the　experimental　findings　and　provide　deeper　insights　into　the　strengthening　mechanism.　This　model　demonstrated　excellent　agreement　with　the　test　results,　confirming　the　effectiveness　of　prestressed　CFRP　plate　strengthening　in　minimizing　joint　deformation　and　reducing　bolt　stresses.　In　summary,　the　study　provides　valuable　insights　into　enhancing　the　structural　integrity　and　durability　of　shield　tunnel　segmental　joints　through　prestressed　CFRP　plate　strengthening.　This　technique　not　only　diminishes　joint　deformations　but　also　enhances　overall　stiffness　and　load-bearing　capacity,　thereby　contributing　to　the　safety　and　longevity　of　tunnel　structures.　©　2024　Institution　of　Structural　Engineers