Strain　engineering　has　attracted　extensive　attention　as　a　valid　method　to　tune　the　physical　and　chemical　properties　of　two-dimensional　(2D)　materials.　Here,　based　on　first-principles　calculations　and　by　solving　the　semi-classical　Boltzmann　transport　equation,　we　reveal　that　the　tensile　strain　can　efficiently　enhance　the　thermoelectric　properties　of　the　GeS2　monolayer.　It　is　highlighted　that　the　GeS2　monolayer　has　a　suitable　band　gap　of　1.50　eV　to　overcome　the　bipolar　conduction　effects　in　materials　and　can　even　maintain　high　stability　under　a　6%　tensile　strain.　Interestingly,　the　band　degeneracy　in　the　GeS2　monolayer　can　be　effectually　regulated　through　strain,　thus　improving　the　power　factor.　Moreover,　the　lattice　thermal　conductivity　can　be　reduced　from　3.89　to　0.48　W/mK　at　room　temperature　under　6%　strain.　More　importantly,　the　optimal　ZT　value　for　the　GeS2　monolayer　under　6%　strain　can　reach　0.74　at　room　temperature　and　0.92　at　700　K,　which　is　twice　its　strain-free　form.　Our　findings　provide　an　exciting　insight　into　regulating　the　thermoelectric　performance　of　the　GeS2　monolayer　by　strain　engineering.　©　2022　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.