Free　standing　centimeter-long　1D　nanostructures　are　highly　attractive　for　electronic　and　optoelectronic　devices　due　to　their　unique　photophysical　and　electrical　properties.　Here　a　simple,　large-scale　synthesis　of　centimeter-long　1D　carbon　nitride　(CN)　needles　with　tunable　photophysical,　electric,　and　catalytic　properties　is　reported.　Successful　growth　of　ultralong　needles　is　acquired　by　the　utilization　of　1D　organic　crystal　precursors　comprised　of　CN　monomers　as　reactants.　Upon　calcination　at　high　temperatures,　the　shape　of　the　starting　crystal　is　fully　preserved　while　the　CN　composition　and　porosity,　and　optical　and　electrical　properties　can　be　easily　tuned　by　tailoring　the　starting　elements　ratio　and　final　calcination　temperature.　The　facile　manipulation　and　visualization　of　the　CN　needles　endow　their　direct　electrical　measurements　by　placing　them　between　two　conductive　probes.　Moreover,　the　CN　needles　exhibit　good　photocatalytic　activity　for　hydrogen　production　owing　to　their　improved　light　harvesting　properties,　high　surface　area,　and　advantageous　energy　bands　position.　The　new　growth　strategy　developed　here　may　open　opportunities　for　a　rational　design　of　CN　and　other　metal-free　materials　with　controllable　directionality　and　tunable　photophysical　and　electronic　properties,　toward　their　utilization　in　(photo)electronic　devices.　©　2018　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim