The Vikings had not been permitted to announce that they were hiring O'Connell while the Rams were still playing in the postseason but can do so anytime now that Los Angeles' season has been completed, culminating with its Super Bowl LVI victory.
The Rams held team meetings and exit interviews Tuesday and will hold their victory parade in Los Angeles on Wednesday.
O'Connell, 36, was one of four candidates to receive a second interview with the Vikings, along with Rams defensive coordinator Raheem Morris, then-Giants defensive coordinator Patrick Graham and Michigan head coach Jim Harbaugh.
O'Connell is expected to take Rams tight ends coach and passing game coordinator Wes Phillips with him to Minnesota as his offensive coordinator or passing game coordinator, league sources have told Schefter. Rams running backs coach Thomas Brown also will interview with the Vikings for their offensive coordinator job, per Schefter.
O'Connell becomes the second coordinator in two years on Sean McVay's staff to land a head-coaching job, joining former Rams defensive coordinator Brandon Staley, who was hired by the Chargers last year.
The Vikings also have their defensive coordinator for O'Connell's staff, finalizing a deal with Ed Donatell last week, sources told ESPN.
O'Connell replaces Mike Zimmer, who was fired last month after eight seasons. The Vikings finished with an 8-9 record and missed the playoffs for a second consecutive season.
O'Connell finished his second season as the Rams' offensive coordinator since joining the franchise in 2020. Before that, he was with Washington for three seasons, as offensive coordinator in 2019, passing game coordinator in 2018 and quarterbacks coach in 2017.