Perdagangan ilegal Harimau Sumatera merupakan ancaman terhadap keberlangsungan spesies yang melibatkan jaringan perdagangan dari tingkat lokal hingga lintas negara. Kompleksitas tersebut menyebabkan implementasi kebijakan penanggulangannya tidak dapat hanya bergantung pada kapasitas pemerintah, tetapi membutuhkan kolaborasi dengan aktor non-negara. Penelitian ini bertujuan menganalisis efektivitas kolaborasi Pemerintah Indonesia dan World Wide Fund for Nature (WWF) dalam implementasi kebijakan penanggulangan perdagangan ilegal Harimau Sumatera. Penelitian menggunakan pendekatan kualitatif dengan metode studi literatur yang bersumber dari jurnal ilmiah, publikasi resmi pemerintah, laporan organisasi internasional, serta dokumen dan publikasi WWF. Data dianalisis melalui dimensi koordinasi, komunikasi, komitmen, dan pembagian sumber daya, sedangkan efektivitas implementasi dianalisis berdasarkan pencapaian tujuan, integrasi, adaptasi, dan monitoring. Perspektif liberalisme institusional digunakan untuk menjelaskan peran institusi dalam memfasilitasi kerja sama, pertukaran informasi, dan tindakan kolektif. Hasil penelitian menunjukkan bahwa kolaborasi Pemerintah–WWF diwujudkan melalui patroli dan pemantauan habitat, pertukaran informasi, dukungan terhadap penegakan hukum, Wildlife Crime Team, penggunaan camera trap, kampanye publik, serta keterlibatan dalam STRAKOHAS dan Tx2. Kolaborasi tersebut memberikan kontribusi terhadap penguatan proses dan keluaran implementasi kebijakan, khususnya dalam pengawasan, monitoring, pertukaran informasi, dan penanggulangan perburuan. Namun, efektivitasnya masih menghadapi keterbatasan berupa cakupan monitoring, ketersediaan sumber daya, kompleksitas koordinasi antarlembaga, dan keberlanjutan jaringan perdagangan ilegal. Dengan demikian, efektivitas kolaborasi lebih tepat dipahami sebagai kontribusi terhadap penguatan kapasitas implementasi kebijakan daripada keberhasilan menghentikan perdagangan ilegal secara menyeluruh. The illegal trade in Sumatran tigers poses a threat to the survival of the species and involves trade networks extending from the local to the transnational level. This complexity means that policy implementation to combat illegal trade cannot rely solely on government capacity but requires collaboration with non-state actors. This study aims to analyze the effectiveness of collaboration between the Indonesian Government and the World Wide Fund for Nature (WWF) in implementing policies to combat the illegal trade in Sumatran tigers. This study employs a qualitative approach using a literature review based on scientific journals, official government publications, international organization reports, and WWF documents and publications. The data are analyzed through the dimensions of coordination, communication, commitment, and resource sharing, while implementation effectiveness is examined through goal achievement, integration, adaptation, and monitoring. Institutional liberalism is employed to explain the role of institutions in facilitating cooperation, information exchange, and collective action. The findings show that Government–WWF collaboration is manifested through habitat patrols and monitoring, information exchange, support for law enforcement, the Wildlife Crime Team, the use of camera traps, public campaigns, and participation in STRAKOHAS and Tx2. The collaboration contributes to strengthening policy implementation processes and outputs, particularly in surveillance, monitoring, information exchange, and anti-poaching efforts. However, its effectiveness remains constrained by limited monitoring coverage, resource availability, the complexity of inter-institutional coordination, and the persistence of illegal trade networks. Therefore, the effectiveness of the collaboration is better understood as a contribution to strengthening policy implementation capacity rather than as evidence of the complete elimination of illegal trade.