This　paper　presents　an　experimental　study　of　the　flexural　performance　of　reinforced　concrete　(RC)　beams　externally　bonded　with　hybrid　fiber-reinforced　polymer　(FRP)　laminates　made　of　carbon　and　polyethylene　terephthalate　(PET)　fibers.　Ten　beam　specimens　were　subjected　to　four-point　bending　tests,　with　a　focus　on　assessing　the　effects　of　the　stacking　sequence　and　the　elastic　modulus　of　hybrid　carbon-PET　FRP　laminates　on　the　flexural　performance　of　the　strengthened　beams.　The　failure　modes,　load-bearing　capacities,　displacement　ductility　of　the　specimens　and　strain　distributions　in　the　FRP　laminates　were　examined　and　discussed.　The　experimental　results　showed　that　the　load-carrying　capacities　of　the　FRP-strengthened　specimens　were　significantly　increased　by　10.18-27.98%,　while　the　displacement　ductility　decreased　by　51.36-77.85%.　The　peak　load　and　ductility　of　the　beam　specimens　strengthened　with　PC　(i.e.,　PET-C　FRP)　and　CPC　(i.e.,　C-PET-C　FRP)　stacking　sequences　were　higher　than　those　of　their　counterparts　strengthened　with　two　or　three　layers　of　hybrid　FRP　laminates.　The　accuracy　and　reliability　of　the　calculation　methods　specified　in　ACI　440.2R-17,　CNR　DT　200　R1/2014　and　GB　50608-2020　for　estimating　the　flexural　strengths　of　the　strengthened　RC　beams　were　evaluated　through　a　comparison　of　theoretical　predictions　with　experimental　results.　The　average　predicted-to-tested　ratios　for　the　flexural　strengths　of　the　strengthened　beams　using　ACI　440.2R-17,　CNR-DT　200　R1/2014　(based　on　PE　debonding　failure),　CNR-DT　200　R1/2014　(based　on　IC　debonding　failure),　and　GB　50608-2020　are　0.994,　0.704,　0.946,　and　0.930,　respectively.