Heterostructured　photosystems　constructed　by　exquisite　interface　engineering　have　sprung　up　in　solar-powered　photocatalysis　and　photoelectrocatalysis,　and　have　been　attracting　enduring　interest　in　the　past　few　decades.　Among　the　diverse　synthesis　strategies,　layer-by-layer　(LbL)　assembly　offers　a　promising　and　robust　platform　for　design　of　multifarious　spatially　multilayered　nanoarchitectures　by　virtue　of　simplicity,　versatility,　easy　accessibility　and　universality.　However,　LbL　self-assembly　of　multilayered　photocatalysts　and　photoelectrodes　are　in　the　infant　stage.　In　this　review,　fundamental　understanding　on　LbL　assembly　including　principle,　molecular　interaction,　influencing　factors,　and　operation　methods　are　concisely　introduced.　Most　importantly,　we　comprehensively　summarized　the　latest　developments　on　LbL　assembly　of　spatially　multilayered　nanoarchitectures　with　multiple　dimensionalities　and　elucidated　their　advantages　in　fabricating　high-performance　photocatalysts　and　photoelectrodes.　Furthermore,　applications　of　LbL-assembled　nanoarchitectures　in　diverse　fields　including　environmental　remediation,　hydrogen　production,　selective　organic　transformation,　and　photoelectrochemical　water　splitting　are　systematically　introduced.　It　is　expected　that　our　review　can　provide　enriched　information　on　rational　design　and　construction　of　LbL　assembled　nanostructures　for　solar　energy　conversion.　©　2023　Elsevier　B.V.