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Objective To explore the long‐term outcome of intracranial‐intracranial side‐to‐side bypass for complex intracranial aneurysms. Methods Five patients with complex intracranial aneurysms underwent intracranial‐intracranial side‐to‐side bypass performed by the same surgeon at The First Hospital of China Medical University from January 2015 to December 2023 were included. Two cases involved the A2 segment of anterior cerebral artery (ACA) and 3 cases involved the M2 segment of middle cerebral artery (MCA). Indocyanine green angiography (ICGA) was used intraoperatively, and CTA or DSA was used postoperatively to evaluate aneurysm occlusion and blood flow reconstruction. The modified Rankin Scale (mRS) was used to evaluate the neurological prognosis at one week, 3 months and the last follow‐up. CT/ MRI examination was completed on the first day, one week and 3 months after operation to evaluate whether hemorrhagic or ischemic complications occurred. Results Five cases of complex intracranial aneurysms were all occluded accurately. Two cases underwent A3‐A3 side‐to‐side anastomosis, and 3 cases underwent M2‐M2 side‐to‐side anastomosis, among which one case added M1‐radial artery (RA)‐M2 intracranialintracranial bypass with RA as graft on the basis of M2‐M2 side‐to‐side anastomosis. During the operation, ICGA confirmed that the side‐to‐side anastomosis and M1‐RA‐M2 bypass were unobstructed in 5 cases. The postoperative follow ‐ up time was 23 (14, 71) months. No aneurysm was found in cerebrovascular imaging examination one week and 3 months after operation in 5 patients, and 9 to 12 months after operation in 3 patients. Five side ‐ to ‐ side anastomosis stomas and one M1 ‐ RA ‐ M2 graft were all unobstructed. At one week after operation, the mRS increased by 0-3 score compared with that before operation (4 score maintained unchanged before and after operation in one case, 2 score increased in one case, and 3 score increased in one case). In 2 unruptured cases, the mRS score was 1 score at one week after operation, and there was no change from that before operation. At 3 months after operation, the mRS scores of 5 cases were decreased (2 cases with 0 score, one case with 2 score, and 2 cases with 3 score); one case was lost at the last follow‐up, and the mRS scores of other 4 cases decreased further (2 cases with 0 score, one case with 1 score, and one case with 2 score). No cerebral hemorrhage or cerebral ischemia occurred in the follow‐up. Conclusions Intracranial‐intracranial side‐to‐side bypass has good short‐term and long‐term patency and stable long‐term clinical effect. It is a reliable technique for surgical treatment of complex intracranial aneurysms.