Background and Objectives: Endovascular mechanical thrombectomy is an important approach for acute ischemic stroke (AIS) treatment. Multimodal neuroimaging methods ideally provide the exact localization, extent, and metabolic activity of target tissues. Post-stroke cognitive impairment has recently been realized to be another major concern except for neurological function impairment. The aim of our study was to carry out a prospective study to compare neurological and cognitive functions after thrombectomy in mild to moderate anterior circulation infarction patients selected by multimodal neuroimaging. Methods: Ninety patients were recruited from January 2016 to March 2017 consecutively. Neurological function was assessed by NIHSS before thrombectomy, and 6 h, 24 h, 7 days, 90 days after mechanical thrombectomy. Cognitive functions were evaluated by Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and Hachinski Ischemic Scale. Results: Patients who received mechanical thrombectomy had significantly better neurological functions at 6 h (p < 0.001), 24 h (p < 0.001), 7 days (p < 0.001), and 90 days (p < 0.001), as well as cognitive functions evaluated by MoCA (26.23 ± 3.85 vs. 24.62 ± 2.25, p = 0.022, n = 85) and MMSE (26.65 ± 2.77 vs. 25.10 ± 2.36, p = 0.023, n = 85) compared to the standard therapy group. Conclusions: The current prospective study demonstrated that mechanical thrombectomy can significantly improve neurological and cognitive functions in patients with mild to moderate AIS at broadened therapeutic window under multimodal CT and multimodal MRI imaging.