The　emergence　of　disruptive　innovation　is　an　important　and　highly　researched　field.　In　the　context　of　innovation　ecosystem,　the　acquisition　and　its　evolution　of　ecosystem　legitimacy　is　an　effective　mechanism　for　start-ups　to　successfully　carry　out　disruptive　innovation.　Prior　research　has　shown　that　disruptive　innovation　is　a　socialized　process　that　involves　collaboration　and　dynamic　interaction　of　multiple　actors.　Therefore,　start-ups　usually　need　to　be　embedded　in　a　suitable　innovation　ecosystem　for　acquiring　relevant　resources　and　capabilities,　in　order　to　realize　disruptive　innovation　through　value　co-creation.　However,　startups　that　introduce　disruptive　innovations　into　an　existing　ecosystem　usually　face　the　liability　of　newness　including　customer　indifference,　incumbent　skepticism,　and　lack　of　co-specialized　assets,　which　will　undermine　the　efforts　and　effects　of　disruptive　innovations　carried　out　by　start-ups.　As　a　result,　in　order　to　successfully　carry　out　disruptive　innovation,　start-ups　usually　have　to　acquire　ecosystem　legitimacy,　that　is,　to　obtain　the　support　from　actors　inside　and　outside　the　ecosystem　or　even　incumbents　that　may　be　disrupted.　However,　it　is　worth　considering　that　there　is　currently　a　lack　of　relevant　research　on　how　start-ups　in　emerging　economies　achieve　disruptive　innovations　through　acquiring　ecosystem　legitimacy.　Although　the　last　few　years　have　seen　a　boom　in　the　study　of　the　relationship　between　innovation　ecosystem　and　disruptive　innovation,　most　of　that　are　usually　based　on　the　assumption　that　disruptive　innovation　has　already　occurred.　Existing　research　focus　mainly　on　the　strategic　response　of　incumbents　to　the　challenge　of　being　disrupted,　with　fewer　studies　analyzing　the　ecosystem　legitimacy　of　disruptive　innovation　carried　out　by　start-ups.　Using　the　method　of　longitudinal　case　study,　this　paper　explores　the　detailed　process　of　how　start-ups　in　emerging　economies　achieve　disruptive　innovation　by　acquiring　the　ecosystem　legitimacy.　According　to　the　principle　of　theoretical　sampling,　Fuzhou　Maixin　Biotechnology　Development　Co.,　Ltd.　was　selected　as　the　case　study　sample.　First,　Maixin　Biotechnology　has　successfully　achieved　disruptive　innovation　and　realized　the　transition　from　entrepreneur　to　leader.　Second,　Maixin　Biotechnology　has　finally　disrupted　or　partially　replaced　the　existing　ecosystem　value　proposition　by　constructing　the　ecosystem　legitimacy.　Moreover,　Maixin　Biotechnology　has　greatly　enhanced　its　disruptive　innovation　capability　through　the　ecological　legitimation　strategies.　Through　the　longitudinal　case　analysis　of　Maixin　Biotechnology　from　1993　to　2023,　this　paper　finds　that　Maixin　Biotechnology　builds　an　innovation　ecosystem　around　a　disruptive　value　proposition,　and　constantly　overcomes　various　obstacles　to　ecosystem　legitimacy　during　this　period,　so　as　to　gradually　get　the　understanding　and　recognition　of　internal　and　external　actors　of　the　ecosystem.　By　acquiring　ecosystem　legitimacy,　Maixin　has　ultimately　succeeded　in　disrupting　or　partially　replacing　the　value　proposition　of　existing　innovation　ecosystems.　In　the　process　of　building　innovation　ecosystems　to　carry　out　disruptive　innovation,　the　ecosystem　legitimacy　construction　of　start-ups　has　experienced　a　dynamic　evolution　from　performative　legitimation,　cognitive　legitimation　to　value　proposition　legitimacy.　Accordingly,　start-ups　could　acquire　ecosystem　legitimacy　through　the　phases　of　behavioral　legitimization,　discursive　legitimation,　and　meaningful　legitimization　in　that　order.　This　paper　introduces　the　perspective　of　ecosystem　legitimacy　which　enriches　the　disruptive　innovation　theory　of　start-ups　in　emerging　economies.　Based　on　the　context　of　Chinese　startups,　this　paper　proposes　a　formation　path　of　disruptive　innovation　through　the　acquisition　of　ecosystem　legitimacy.　This　paper　not　only　makes　up　for　the　traditional　deficiency　from　the　single　perspective　of　incumbents　to　examine　disruptive　innovation,　but　also　provides　a　new　mechanism　for　disruptive　innovation　of　Chinese　start-ups.　The　conclusion　has　also　important　enlightenment　for　the　disruptive　innovation　practice　of　start-ups　in　emerging　economies　and　the　construction　of　scientific　and　technological　powerhouse　of　China.　©　2024　Editorial　Department　of　Studies　in　Science　of　Science.　All　rights　reserved.