Dallas Cowboys
On November 24, 2010, Sendejo was signed to the Dallas Cowboys' practice squad as an undrafted free agent. On November 29, 2010, Sendejo was promoted to the active roster. He played in a pair of games, making his NFL debut against the Philadelphia Eagles (12/12). He notched a special teams tackle against the Washington Commanders (12/19). He was waived on September 3, 2011.
New York Jets
Sendejo was claimed by the New York Jets off waivers on September 4, 2011. He was cut by the Jets on September 13. The Jets re-signed Sendejo to their practice squad on September 14, after he cleared waivers. He was released on September 27.
Minnesota Vikings
On November 29, 2011, he was signed as a free agent by the Minnesota Vikings and started the last three games at safety. In 2012, he ranked fourth on team in special teams tackles (11).
In 2013, he started 10 games at strong safety in place of an injured Harrison Smith. He finished third on team with 104 tackles and on December 8, he picked off Joe Flacco, getting the first interception of his career. He was third on the team with 13 special teams tackles.
In 2014, he led the team with 13 special teams tackles and started the last 3 games in place of an injured Robert Blanton.
In 2015, he started 13 games at strong safety, registering 74 tackles, 3 passes defensed and one interception. In the season opener, he blocked a field goal, which was returned by Marcus Sherels into San Francisco 49ers territory. He had one interception of Eli Manning against the New York Giants.
On March 5, 2016, Sendejo agreed to a four-year, $16 million contract extension with the Vikings.
In 2016, Sendejo started 14 games recording 72 tackles, four pass breakups and two interceptions. He was placed on injured reserve on December 31, 2016 with a knee injury.
In Week 7 of the 2017 season, Sendejo made helmet contact with Ravens' receiver Mike Wallace, forcing Wallace to leave with a concussion. The next day, Sendejo was suspended one game for violating league player safety rules.