A　first-principles　theoretical　study　of　the　enhanced　electronic　and　magnetic　properties　of　a　single-layer　CdS　(denoted　as　SL-CdS)　was　conducted　via　Li　substitutional　doping　at　possible　sites.　Previous　work　shows　that　SL-CdS　is　a　non-magnetic　and　direct　bandgap　semiconductor.　Our　work　demonstrated　that　electronic　bandgap　tuned　to　smaller　and　larger　values,　e.g.,　the　calculated　bandgap　(pseudo　bandgap)　for　LiCd　(Lih)　are　1.80　eV　and　1.62　eV,　respectively.　Local　magnetic　moment　induced　via　Li　atomic　doping　at　possible　dopants　sites　except　for　Lih.　The　LiCd　gives　a　maximum　magnetic　moment　of　0.98　μB　and　shows　the　half-metallic　character　with　a　small　dispersion　for　the　spin-down　channel　at　the　Γ　point.　Among　all　the　possible　sites,　the　LiCd　in　SL-CdS　is　magnetic　and　being　most　favorable　thermodynamically　under　both　S-rich　and　Cd-rich　conditions.　The　LiCd　in　SL-CdS　indicates　spin　polarization　with　increased　bandgap　for　spin-up　and　spin-down　channels.　In　contrast,　the　LiS　induces　a　magnetic　moment　of　0.86　μB　with　a　reduced　bandgap　of　0.60　eV　for　both　the　spin-up　and　spin-down　channels.　The　partial　magnetic　moment　is　due　to　the　fact　small　concentration　of　the　dopant.　Interestingly,　Lih　in　SL-CdS　shows　non-magnetic　semiconducting　nature　with　decreased　bandgap.　For　further　investigation,　we　considered　the　most　favorable　Cd-Site.　For　room-temperature　ferromagnetism,　we　did　ferromagnetic　and　anti-ferromagnetic　calculations.　We　considered　interactions　between　two　Li　atoms　substituted　at　far　positions　(1,　2)　and　near　positions　(1,　3)　in　SL-CdS.　It　was　found　that　2LiCd　in　SL-CdS　at　near　positions　(1,　3)　has　FM　order　with　Curie　temperature　(Tc)　of　339.95　K　at　−　5%　compressive　biaxial　strain.　The　effect　of　Li　doping　on　electronic　and　magnetic　properties　of　SL-CdS　can　help　to　utilize　SL-CdS　materials　in　electronics　and　spintronics　devices　applications.　©　2021　Elsevier　Ltd