Background: Low-value services, which provide minimal patient benefit while entailing costs and risks, are prevalent in cancer care. Shifts in cancer care delivery during the COVID-19 pandemic to minimize exposure provided opportunities for health systems and clinicians to prioritize higher-value over low-value oncology services. Methods: In this retrospective cohort study, we investigated the association between the COVID-19 pandemic period and low-value cancer care practices using administrative claims from the HealthCore Integrated Research Environment, consisting of ̃65 million members managed by 14 health plans across the US. We identified commercial or Medicare Advantage members diagnosed with breast, colorectal, or lung cancer between January 2015 and March 2021. Low-value cancer care practices were identified from peer-reviewed medical literature, including ASCO and ASTRO Choosing Wisely campaigns and evidence-based pathways. Five low-value practices were studied: (1) conventional fractionation instead of hypofractionation for early-stage breast cancer; (2) off-pathway systemic therapy; (3) non-guideline-based antiemetic use for minimal-, low-, or moderate-to-high-risk chemotherapies; (4) Positron Emission Tomography/Computed Tomography (PET/CT) instead of conventional CT for staging; and (5) aggressive end-of-life care (chemotherapy ≤14 days, multiple emergency department visits ≤30 days, ICU utilization ≤30 days, hospice initiation ≤3 days, and/or no hospice before death). We used linear probability models to evaluate the association between the COVID-19 period (March to December 2020) and the 5 outcomes, adjusting for patient, facility, geographic and temporal characteristics. Results: Among 204,581 members (mean age 63.1, 139,488 [68.1%] female), 83,593 (40.8%) had breast cancer, 56,373 (27.5%) had colon cancer, and 64,615 (31.5%) had lung cancer. Rates of low-value care were similar in pre-COVID vs. COVID periods: conventional radiotherapy: 22.1% vs. 9.4%; off-pathway systemic therapy: 36.7% vs. 43.2%; non-guideline-based antiemetics: 61.2% vs. 58.1%; PET/CT imaging: 39.9% vs. 41.3%; aggressive end-of-life care: 75.8% vs. 73.3%. In adjusted analyses, the COVID-19 period was associated with no changes in off-pathway therapy (adjusted percentage point difference [aPPD] 0.82, SD 0.08, p = 0.33), PET/CT imaging (aPPD 0.10, SD 0.005, p = 0.83), and aggressive end-of-life care (aPPD 2.71, SD 0.02, p = 0.16). Small changes in conventional radiotherapy (aPPD 3.93, SD 0.01, p < 0.01) and non-guideline-based antiemetics (aPPD -3.62, SD 0.006, p < 0.01), were noted. Conclusions: The shock of the COVID-19 pandemic did not meaningfully change several metrics of low-value cancer care. Broader changes to payment and incentive design should be considered to turn the tide toward higher-value cancer care.