With　rising　global　concerns　about　the　discharge　of　large　volumes　of　waste　materials　derived　from　industrial　manufacture　and　human　life,　methods　for　utilizing　waste　materials　have　been　greatly　developed.　In　this　study,　an　ingenious　hydroxyapatite　(Hap)　functionalized　hierarchical　porous　biochar　(HB)　composite　is　fabricated　using　a　filtrate　rich　in　Ca2+　ions　after　steel　slag　reuse　and　spent　Hami　melon　peel　as　raw　materials.　Microstructural　analyses　indicate　that　Hap　nanoparticles　are　loaded　on　HB　with　hierarchical　pores　produced　from　a　pyrolysis　process　of　Hami　melon　peel.　A　series　of　HB-Hap　materials　by　tuning　HB　addition　amount　(0.5,　1,　and　2　g)　can　be　obtained　through　a　coprecipitation　process.　As　a　case　study,　HB-0.5Hap　exhibits　high　specific　surface　area　of　66.92　m(2)/g　and　high-efficiency　removal　performance　for　Pb(II)　and　Cd(II)　ions　in　wastewater.　The　maximum　adsorption　capacities　of　HB-0.5Hap　are　134.4　(Pb(II))　and　60.4　(Cd(II))　mg/g,　which　are　1.77　and　1.23　times　higher　than　that　of　pure　HB,　respectively.　It　is　attributed　to　a　synergistic　mechanism　involving　ion　exchange,　chemical　precipitation,　surface　complexation,　and　cation-pi　interaction.　According　to　a　semi-quantitative　calculation,　ion　exchange　plays　a　major　role　in　the　removal　of　Pb(II)　(78.61%,　the　relative　contribution　of　ion　exchange　mechanism)　and　Cd(II)　(77.77%).　This　study　demonstrates　a　facile,　economical,　and　sustainable　strategy　for　the　value-added　utilization　of　steel　slag　and　spent　Hami　melon　peel,　which　can　be　critical　in　solving　environmental　problems.