Forced or coerced sexual experiences have serious consequences for young people’s health and well-being. Healthy sexual consent communication can foster positive intimate relationships and help prevent unwanted sexual experiences. We aimed to explore how young people in Nairobi’s informal settlements construct, communicate, and negotiate sexual consent within heterosexual partnerships, given the limited insight into such experiences from resource-poor, global-south contexts. A qualitative study with young men and women aged 15 to 21 years was conducted among former participants of a school-based sexual violence prevention intervention in four informal settlements (slums) of Nairobi. Twenty-one individual in-depth interviews ( n = 10 females, n = 11 males) and 10 focus group discussions (five with n = 6–11 males vs. females, respectively), that is, n = 89 in total were conducted. Data were analysed using thematic network analysis and interpreted using the Sexual script theory. Participants’ endorsement of incongruent sexual scripts shaped their perceptions and negotiations of sexual consent. Young men were committed to respecting sexual consent, but promoted male (sexual) dominance, and perceived women’s refusals as token resistance. Per traditional scripts of sexual chastity, young women were largely bound by their use of a “soft no” to give consent, so as to not display direct sexual interest. Actual non-assertive refusals thus risked being interpreted as consent. Young women’s “actual” refusals had to be more assertive (saying a “hard no”) and were described as having been influenced by skills learned during the school-based intervention. Findings highlight the need for sexual consent education to address internalized gendered norms about female token resistance, destigmatize female sexuality, reduce male dominance norms, and encourage young people’s respect for both assertive and non-assertive sexual consent communication.