Immune hyperactivation has been linked to various vaccines. We present a potential association of newonset systemic lupus erythematosus (SLE) post-COVID-19 immunization. The patient is a 54-year-old male admitted for evaluation of flu-like symptoms two weeks after receiving the second dose of the COVID-19 vaccine. Physical examination revealed high-grade fever, diffuse bilateral non-tender cervical lymphadenopathy, and erythematous maculopapular palpable purpuric lesions on bilateral feet. Laboratory evaluation showed a significant hypocomplementemia (C3 < 11 mg/dL, C4 < 3 mg/dL, and CH50 < 10 U/mL), high titer antinuclear antibody, anti-dsDNA antibodies, anti-Sjogren's syndrome-related antigen A antibodies, anti-Sjogren's syndrome-related antigen B antibodies, anti-Smith antibodies, antiribonucleoprotein antibodies, anti-histone antibodies with a negative malignancy, and infection workup. The patient was treated with a high dose of steroids with a positive response. This case highlights the possibility of SLE, a rare adverse event following COVID-19 vaccination.