A　direct　joining　of　sapphire　and　Fe–36Ni　alloy　was　successfully　realized　via　femtosecond　laser　micro-welding　for　the　first　time.　A　sound　joint　without　any　voids　or　microcracks　was　obtained　with　a　narrow　interface　width　less　than　1　μm.　There　was　no　obvious　element　diffusion　or　metallurgical　reactions　at　the　interface.　Sapphire　and　Fe–36Ni　alloy　were　found　chemically　bonded　and　mechanically　interlocked　evidenced　by　jagged　feature　at　the　interface　due　to　“cold”　machining　of　femtosecond　laser　ablation.　The　highly　localized　femtosecond　laser　irradiation　and　smaller　heat-affected　zone　contributed　to　the　shear　strength　of　the　joint　as　high　as　108.35　MPa.　A　higher　laser　scanning　speed　corresponded　with　less　jagged　feature　and　thermal　stress　due　to　the　reduced　thermal　deposition　at　the　interface.　Proper　micro-welding　parameters　were　obtained　for　sapphire/Fe–36Ni　alloy,　and　was　verified　in　the　direct　joining　of　sapphire/steel　and　sapphire/silicon.　It　appears　the　femtosecond　laser　micro-welding　technique　is　promising　for　direct　joining　of　materials　with　large　physical　property　disparities,　and　beneficial　for　manufacturing　of　optomechanical　components　at　high　precision,　efficiency　and　performance.　©　2023