PurposeTo assess epilepsy, motor function, cognitive, sleep, and quality of life outcomes and their predictors in a follow-up cohort with West syndrome (WS) at ≥5 years of age. MethodsCross-sectional evaluation in a follow-up cohort of WS (aged 5–14 years), between July 2018 and December 2019, was performed at a tertiary-care referral center in Northern India. 164 children were assessed in-person for epilepsy severity, functional status (gross motor and hand function), social quotient, behavioral comorbidities, sleep problems, and quality of life (QoL) using Early Childhood Epilepsy Severity Scale, Gross Motor Function Classification System, Manual Ability Classification System, Vineland Social Maturity Scale, Diagnostic and Statistical Manual of Mental disorders-5 criteria, Children’s Sleep Habits Questionnaire, and PedsQL-Epilepsy module respectively. Furthermore, 238 children with the inability to visit the hospital were assessed through telephonic interview along with retrospective case record review for epilepsy control, gross and fine motor measures. Results402 children with WS (75 % boys) with regular follow-up were studied and the majority (80 %) had underlying structural etiology. The median age (interquartile range) of the cohort was 92 (78–107) months. Of these, 60 % had evolved to Lennox-Gastaut syndrome (LGS). The following long-term outcomes were observed: ongoing epilepsy (261/402), unfavorable motor status (130/402), moderate to profound intellectual disability (111/164), autistic spectrum disorder (42/164), attention-deficit hyperactivity disorder (18/164), poor sleep (135/164), and impaired QoL (115/164). Non-structural etiology (odds ratio [OR] = 3.8, 95 % confidence interval [CI]: 2.1−5.5, p=<0·0001) and older age (>5 months) at the onset of epileptic spasms (OR = 2·9, 95 % CI: 1.5−5.0, p=<0·0001) were associated with enduring seizure freedom for more than two years. ConclusionThe present study revealed a preponderance of structural etiology and a high rate of transition to LGS. Early age at onset of spasms (before five months) and structural etiology were the predictors of unfavorable long-term epilepsy outcome. QoL was impaired in more than two-thirds of patients and it correlated significantly with cognitive, sleep, motor, and behavioral outcomes. However, the results of our study should be interpreted in the context of significant attrition of the original cohort.