Background: Our recent study showed that the implementation of the Affordable Care Act (ACA) was associated with increased health insurance coverage among adolescents and young adults (AYAs, 15–39 years) diagnosed with lymphomas in California and decreased likelihood of late stage at diagnosis. However, AYAs of Black or Hispanic race/ethnicity (vs Whites) and those living in lower socioeconomic (SES) neighborhoods were at higher risk of presenting with advanced stage. We aimed to determine whether the increased insurance coverage under the ACA was associated with improved survival, and to identify the main predictors of survival among AYAs with lymphomas. Methods: We used data from the California Cancer Registry linked to Medicaid enrollment files on AYAs diagnosed with a primary non-Hodgkin (NHL) or Hodgkin (HL) lymphoma during March 2005–September 2010 (pre-ACA), October 2010–December 2013 (early ACA) or 2014–2017 (full ACA). Patients were followed from lymphoma diagnosis until death, loss to follow-up or end of the study (12/31/2018). Health insurance was categorized as continuous Medicaid, discontinuous Medicaid, Medicaid enrollment at diagnosis/uninsured, other public or private. We used multivariable Cox proportional regression to examine the associations between all-cause survival and era of diagnosis, adjusting for sex, age and stage at diagnosis, health insurance, race/ethnicity, neighborhood SES, treatment facility, comorbidities, and marital status. Results: Of 11,221 AYAs, 5,878 were diagnosed with NHL and 5,343 with HL. Most patients were male (56%), White (45%), presented with earlier stage (I/II, 56%), and had private insurance (57%). The proportion of AYAs who received initial care at National Cancer Institute-Designated Cancer Centers (NCI-CCs) increased from 24% pre-ACA to 31% after full ACA implementation (p < 0.001). AYAs diagnosed in the early (aHR = 0.76, 95% CI 0.67–0.88) and full ACA (aHR = 0.55, 95%CI 0.47–0.64) eras had better survival than those diagnosed pre-ACA. Compared to those with private insurance, survival was worse among patients with no insurance (HR = 2.13, 95% CI 1.83–2.49), discontinuous Medicaid (HR = 2.17, 95% CI 1.83–2.56) and continuous Medicaid (HR = 1.93, 95% CI 1.63–2.29) at diagnosis. Regardless of their insurance, older AYAs, males, unmarried, those with later stage (II–IV), residents in lower SES neighborhoods, and those of Black, Hispanic, Asian/Pacific Islander, and American Indian/Alaskan Native race/ethnicity experienced worse survival. Conclusions: Following the ACA implementation in California, AYAs diagnosed with lymphomas experienced increased access to care at NCI-CCs and improved survival. Yet, racial/ethnic and socioeconomic survival disparities persisted. Moving forward, policy actions are required to mitigate structural and social determinants of health disparities in this population.