[3] Vaněček continued his career the following season in North America, splitting time between playing for the South Carolina Stingrays and the Hershey Bears, affiliates to the Capitals.

[7] He would go on to be named MVP of the event after leading the Atlantic Division to a championship, only allowing two goals in four games.

[10][11] Vaněček started in his first NHL game on 15 January 2021, saving 30 of 31 shots and earning his first victory as the Capitals defeated the Buffalo Sabres 2–1.

[17] As a restricted free agent, Vaněček was later signed to a three-year, $10.2 million contract extension with the Devils on 19 July.

[18] On 8 March 2024, Vaněček along with a 2025 seventh-round pick was traded to the San Jose Sharks in exchange for Kaapo Kähkönen.