There are no studies on time to test since notification among identified sexual contacts of HIV-positive index clients using program data in Siaya County and Kenya. We sought to understand time to HIV testing by contact characteristics after identification to inform targeted testing interventions. We retrospectively analyzed data from adult (aged ≥18 years) sexual contacts identified by HIV-positive index clients from 117 health facilities in Siaya County (June 2017-August 2018). We used Chi-square tests to assess for differences in characteristics of contacts by HIV testing. We performed Cox proportional hazards analysis and time to HIV testing of contacts analysis including time-varying covariates (cluster-adjusted by facility) to assess characteristics (age, sex, and relationship to index client) associated with time to HIV-testing since notification. Sexual contacts not tested were right censored at last follow-up date. We calculated hazard ratios with 95% confidence intervals to evaluate characteristics associated with time to testing. Of the 6,845 contacts included in this analysis, 3,858 (56.4%) were men. Most were aged 25-34 years (3,209 [46.9%]). Median time to contact testing was 14.5 days (interquartile range, 2.5-62). On multivariable analysis, contacts aged 18-24 years (aHR, 1.32 [95% CI: 1.01-1.73], p = 0.040) and 25-34 years (aHR, 1.18 [95% CI: 1.01-1.39], p = 0.038) had shorter time to HIV testing than those aged 35-44 years. Married polygamous (aHR, 1.12 [95% CI: 1.01-1.25], p = 0.039) and single contacts (aHR, 1.17 [95% CI: 1.08-1.27], p <0.001) had shorter time to HIV testing than married monogamous contacts. Non-spouse sexual contacts had shorter time to HIV testing than spouses, (aHR, 1.23 [95% CI: 1.15-1.32], p <0.001). We recommend enhanced differentiated partner services targeting older adults, married monogamous, and spouse sexual contacts to facilitate early diagnosis, same day treatment, and prevention in Western Kenya and sub-Saharan Africa at large.