Quantum　dots　have　innate　advantages　as　the　key　component　of　optoelectronic　devices.　For　white　light-emitting　diodes　(WLEDs),　the　modulation　of　the　spectrum　and　color　of　the　device　often　involves　various　quantum　dots　of　different　emission　wavelengths.　Here,　we　fabricate　a　series　of　carbon　quantum　dots　(CQDs)　through　a　scalable　acid　reagent　engineering　strategy.　The　growing　electron-withdrawing　groups　on　the　surface　of　CQDs　that　originated　from　acid　reagents　boost　their　photoluminescence　wavelength　red　shift　and　raise　their　particle　sizes,　elucidating　the　quantum　size　effect.　These　CQDs　emit　bright　and　remarkably　stable　full-color　fluorescence　ranging　from　blue　to　red　light　and　even　white　light.　Full-color　emissive　polymer　films　and　all　types　of　high-color　rendering　index　WLEDs　are　synthesized　by　mixing　multiple　kinds　of　CQDs　in　appropriate　ratios.　The　universal　electron-donating/withdrawing　group　engineering　approach　for　synthesizing　tunable　emissive　CQDs　will　facilitate　the　progress　of　carbon-based　luminescent　materials　for　manufacturing　forward-looking　films　and　devices.