Purpose: The epidemiology of B-cell non-Hodgkin lymphoma (BNHL) in Asia is not well described, and rates of second primary malignancies (SPM) in these patients are not known. We aimed to describe temporal changes in BNHL epidemiology and SPM incidence in Korea. Materials and Methods: A retrospective cohort study used claims data from the National Health Insurance Service that provides universal healthcare coverage in Korea. Newly diagnosed patients aged at least 19 years with a confirmed diagnosis of one of six BNHL subtypes (diffuse large cell B-cell lymphoma [DLBCL], small lymphocytic and chronic lymphocytic [CLL/SLL], follicular lymphoma [FL], mantle cell lymphoma [MCL], marginal zone lymphoma [MZL], and lymphoplasmacytic lymphoma/Waldenström’s macroglobulinemia [WM]) during the period 2006-2015 were enrolled and followed up until death, dis-enrolment, or study end, whichever occurred first. Patients with pre-existing primary cancers prior to the diagnosis of BNHL were excluded. Results: A total of 19,500 patients with newly diagnosed BNHL were identified out of 27,866 with non-Hodgkin lymphoma (NHL). DLBCL was the most frequently diagnosed subtype (41.9%-48.4% of NHL patients annually, 2011-2015). Standardized incidence of the six subtypes studied per 100,000 population increased from 5.74 in 2011 to 6.96 in 2015, with most increases in DLBCL, FL, and MZL. The incidence (95% confidence interval) of SPM per 100 person-years was 2.74 (2.26-3.29) for CLL/SLL, 2.43 (1.57-3.58) for MCL, 2.41 (2.10-2.76) for MZL, 2.23 (2.07-2.40) for DLBCL, 1.97 (1.61-2.38) for FL, and 1.41 (0.69-2.59) for WM. Conclusion BNHL has been increasingly diagnosed in Korea. High rates of SPM highlight the need for continued close monitoring to ensure early diagnosis and treatment.