Background The UK pledged commitment to the global strategy of zero new HIV infections and HIV-related deaths by 2030. PrEP was commissioned in England in 2020 and is fundamental to achieving these targets, yet awareness and uptake are suboptimal in certain populations. Method Sexual Health London (SHL) incorporated questions on its e-triage questionnaire estimating need for PrEP amongst online service users. Two types of signposting messaging were shown to users directing them to more detailed online content: PrEP-discussion (potential need) and PrEP-eligible (assumed need). The effectiveness of this signposting was evaluated by reviewing demographics and triage responses in returning users. Results 426,149 SHL users requested STI screening between 1.7.21-31.10.22. 16% (69,867/426,149) and 32.2% (137,489/426,149) of individuals received PrEP-eligible and PrEP-discussion signposting. The PrEP-eligible cohort were: 41.0% gay/bisexual or other men who have sex with men (GBMSM), 16.3% heterosexual males, 33.1% heterosexual females, and 60.6% were of white ethnicity. The PrEP-discussion cohort were: 9.3% GBMSM, 34.3%% heterosexual males, 45.5% heterosexual females and 63.7% of white ethnicity. 50.4% (35,190/69,867) and 41.3% (56,808/137,489) of the PrEP-eligible and PrEP discussion cohorts ordered a subsequent SHL STI testing kit, during which 10.0% (3510/35,190) and 5.9% (3364/56,808) reported taking PrEP. Of those who denied taking PrEP, 59% (18,702/31,680) and 61.0% (32,559/53,444) triggered PrEP signposting again. 95.4% of PrEP starters were GBMSM (6562/6874) and 1.4% (97/6874) heterosexual males/females. Conclusion The e-service demonstrated feasibility in estimating PrEP need and signposting service users. Up to 16% of returning users subsequently commenced PrEP. This highlights significant missed opportunities for the remaining online users, who continue to report HIV acquisition risk(s). Further efforts regionally/nationally to optimise uptake of PrEP, particularly among under-represented groups are warranted.