In the era of global transformation, problem-solving, cognitive, and social skills are becoming increasingly essential, while physical skills are declining in relevance. The government promotes deep learning as a student-centered approach that emphasizes 21st-century skills such as collaboration, creativity, and critical thinking. Additionally, the integration of the STEM (Science, Technology, Engineering, and Mathematics) approach in education is becoming increasingly urgent to equip students for future challenges. This study was motivated by the low levels of collaboration, creativity, and critical thinking skills among Grade VIII students at SMP XYZ, as well as the suboptimal integration of the STEM approach in classroom practices. The purpose of this research is to enhance these three competencies through the implementation of the STEM approach using the seven steps of the Engineering Design Process. The research employed a Classroom Action Research (CAR) method conducted in three cycles, each consisting of planning, action, observation, and reflection stages. The CAR method was chosen for its practical and reflective nature, allowing for immediate adjustments based on classroom conditions. The subjects of the study were 31 Grade VIII students. Data were collected through questionnaires, observations, interviews, and field notes. The average collaboration scores increased from 79.3 in the first cycle to 83.9 in the second and 91.0 in the third. Creativity scores rose from 78.2 to 78.6 and 89.4, while critical thinking scores improved from 84.3 to 85.3 and 90.6 across the cycles. The results indicate that the implementation of the STEM approach in mathematics learning on the topic of circles effectively enhances students’ collaboration, creativity, and critical thinking skills./ Di era transformasi global, keterampilan memecahkan masalah, kognitif, dan sosial semakin penting, sementara keterampilan fisik mengalami penurunan relevansi. Pemerintah mendorong pembelajaran mendalam (deep learning) yang berpusat pada siswa dan menekankan keterampilan abad ke-21, seperti kolaborasi, kreativitas, dan berpikir kritis. Selain itu, integrasi pendekatan STEM (Science, Technology, Engineering, and Mathematics) dalam pembelajaran menjadi semakin mendesak untuk membekali siswa menghadapi tantangan masa depan. Penelitian ini dilatarbelakangi oleh rendahnya kemampuan kolaborasi, kreativitas, dan berpikir kritis siswa kelas VIII di SMP XYZ, serta belum optimalnya penerapan pendekatan STEM secara integratif dalam proses pembelajaran. Tujuan penelitian ini adalah meningkatkan ketiga kemampuan tersebut melalui penerapan pendekatan STEM dengan menggunakan tujuh langkah desain teknik (Engineering Design Process). Metode yang digunakan adalah Penelitian Tindakan Kelas (PTK) yang dilaksanakan dalam tiga siklus, masing-masing terdiri dari tahap perencanaan, pelaksanaan tindakan, observasi, dan refleksi. Penggunaan metode Penelitian Tindakan Kelas dilakukan untuk menyelidiki praktik pendekatan pembelajaran STEM di kelas serta melakukan penyesuaian secara langsung sesuai dengan keadaan kelas, karena sifatnya yang praktis dan reflektif. Subjek penelitian adalah 31 siswa kelas VIII. Data dikumpulkan melalui angket, observasi, wawancara, dan catatan lapangan. Nilai rata-rata kolaborasi pada siklus satu adalah 79.3, siklus dua 83.9, dan siklus tiga 91.0. Nilai rata-rata kreativitas pada siklus satu adalah 78.2, siklus dua 78.6, dan siklus tiga 89.4. Nilai rata-rata berpikir kritis pada siklus satu adalah 84.3, siklus dua 85.3, dan siklus tiga 90.6. Hasil penelitian menunjukkan bahwa penerapan STEM dalam pembelajaran Matematika pada topik lingkaran dapat meningkatkan kemampuan kolaborasi, kreativitas, serta berpikir kritis.