"Yes yes yes it will always be yes," Benoist captioned a photograph of Wood kissing her on the cheek, with her engagement ring on full display.
Wood shared the same photograph and wrote: "The happiest."
They both met on the set of TV series "Supergirl", in which Benoist stars as the lead character.
The 30-year-old actress was previously married to "Glee" star Blake Jenner. But due to irreconcilable differences, she filed for divorce in 2016 and officialy got separated from him in 2017.