Removal　of　indoor　formaldehyde　is　important　but　challenging　due　to　the　very　low　concentration.　Here,　we　showed　the　applicability　of　a　new　class　of　conjugated　microporous　poly(aniline)s　(CMPAs)　in　this　formaldehyde　capture.　The　unique　properties　of　rich　ultramicroporosity　and　benzenoid　amine　(–NH–)　groups　made　the　resulting　CMPAs　ideal　platforms　for　the　efficient　low-concentration　formaldehyde　adsorption,　through　the　interaction　between　benzenoid　amine　groups　and　formaldehyde　via　Mannich　reaction　and　H-bond　in　the　ultramicropore.　They　therefore　exhibited　ultrafast　adsorption,　receiving　＞　80%　removal　efficiency　for　ca　0.7　ppm　formaldehyde　within　60　min,　and　benchmarking　storage　capacity,　achieving　ca.　2679.68　mg·g−1　for　CMPA-2.　Our　CMPAs　also　worked　well　in　a　self-assembled　air　clean　unit,　keeping　kinetically　reducing　average　98%　of　formaldehyde　after　treatment　of　4000　BV　polluted　air　(with　ca.　25　ppm　formaldehyde)　without　break-through.　Outcomes　highlighted　the　potential　of　CMPAs　for　the　clean-up　of　airborne　formaldehyde　for　human　health　protection　in　next　generation.　©　2021　Elsevier　Ltd