Pre-draft On November 20, 2017, it was announced that Warner had accepted his invitation to play in the
2018 Senior Bowl. On January 27, 2018, Warner recorded six combined tackles as part of
Denver Broncos' head coach
Vance Joseph's North team that lost 45–16 to the South coached by
Houston Texans' head coach
Bill O'Brien. His overall performance throughout the week impressed scouts and helped him add value to his draft stock. He attended the
NFL Scouting Combine and completed all of the combine drills. He finished 13th among all linebackers in the 40-yard dash, eighth in the bench press, ninth in the short shuttle, and sixth in the three-cone drill. Warner attended pre-draft visits and private workouts with multiple teams, including the
San Francisco 49ers, Broncos, and
Buffalo Bills. At the conclusion of the pre-draft process, Warner was projected to be a second round pick by the majority of NFL draft experts and scouts. He was ranked the fourth best outside linebacker in the draft by
Scouts Inc. and was ranked the sixth best outside linebacker by DraftScout.com.
2018 season The 49ers selected Warner in the third round with the 70th overall pick in the
2018 NFL draft. Warner was the ninth linebacker drafted in 2018. On June 13, 2018, the 49ers signed Warner to a four-year, 3.97 million contract that includes a
signing bonus of $1.01 million. Throughout
training camp, Warner competed against
Brock Coyle to be the starting middle linebacker. Head coach
Kyle Shanahan named Warner the starting middle linebacker to begin the season. He started alongside outside linebackers
Mark Nzeocha and
Malcolm Smith. Warner made his NFL debut and first start in the season-opener against the
Minnesota Vikings and recorded 12 combined tackles (11 solo tackles), one pass defended, and one forced fumble during a 24–16 road loss. In the regular-season finale, he collected a season-high 14 combined tackles (nine solo) in a 48–32 road loss to the
Los Angeles Rams in Week 17. Warner started all 16 games during his rookie year and recorded 124 combined tackles (85 solo), six pass deflections, and one forced fumble. Warner's 124 total tackles finished 12th among all players and third among all rookies in 2018.
2019 season and
Dre Greenlaw in a game against the
Washington Redskins Warner announced he would change his number from 48 to 54 for the 2019 season, after the departure of
Cassius Marsh. In Week 10 against the
Seattle Seahawks on
Monday Night Football, Warner recorded a team high 10 tackles, sacked
Russell Wilson twice, and forced a fumble on offensive tackle
Germain Ifedi which was recovered by teammate
DeForest Buckner for a 12 yard touchdown in a 27–24 overtime loss. Two weeks later, Warner recorded 11 tackles, a tackle for loss, and strip-sacked
Aaron Rodgers in a 37–8 victory over the
Green Bay Packers, earning
National Football Conference (NFC) Defensive Player of the Week honors. Warner was named the NFC Defensive Player of the Month for his play in November. During Week 16 against the Rams, Warner recorded 11 tackles and an interception off a pass thrown by
Jared Goff, which he returned 46 yards for his first NFL touchdown in a narrow 34–31 victory. During
Super Bowl LIV against the
Kansas City Chiefs, Warner recorded seven tackles and intercepted a pass thrown by
Patrick Mahomes during the 31–20 loss. He was ranked 70th by his peers on the
NFL Top 100 Players of 2020.
2020 season On August 31, 2020, Warner was placed on the
COVID-19 reserved list by the team, before he was activated on September 9. In Week 3 against the
New York Giants, Warner recorded his first interception of the season during the 36–9 win. In Week 16, Warner racked up 14 tackles, three passes defended, a forced fumble and a fumble recovery in a 20–12 win over the
Arizona Cardinals, earning NFC Defensive Player of the Week. In Week 17 against the Seahawks, Warner led the team with 10 tackles and recorded his first sack of the season on
Russell Wilson during the 26–23 loss. Warner totaled one sack, 125 total tackles, two interceptions, six passes defended, and one forced fumble in 16 games and starts. The season culminated in Warner earning his first
Pro Bowl selection, and first ever honor as
Associated Press First-team
All-Pro. He was ranked 21st by his fellow players on the
NFL Top 100 Players of 2021.
2021 season On July 21, 2021, Warner signed a record-breaking five-year extension with the 49ers worth $95 million along with $40.5 million guaranteed. In the 2021 season, Warner appeared in and started 16 regular season games and three postseason games. He had .5 sacks, 137 total tackles, four passes defended, and one forced fumble. He was ranked 47th by his fellow players on the
NFL Top 100 Players of 2022.
2022 season In the 2022 season, Warner started in all 17 regular season games and three postseason games for the 49ers. He had two sacks, 130 total tackles, one interception, ten passes defended, and one forced fumble. He earned Pro Bowl and first team All-Pro honors. He was ranked 15th by his fellow players on the
NFL Top 100 Players of 2023.
2023 season In Week 5 of the 2023 season, against the
Dallas Cowboys, Warner made a team-leading eight solo tackles, one interception, one forced fumble (on running back
Tony Pollard), and a sack on quarterback
Dak Prescott. He won NFC Defensive Player of the Week. The 49ers won at home 42–10. He earned Pro Bowl and first team All-Pro honors for the season. In the 2023 season, Warner had 2.5 sacks, 132 total tackles (82 solo), four interceptions, 11 passes defended, and four forced fumbles in 17 games and starts. Warner had a team-leading 13 total tackles in
Super Bowl LVIII, a 25–22 loss in overtime to the Chiefs. Warner was ranked 11th by his fellow players on the
NFL Top 100 Players of 2024.
2024 season In the 49ers' season debut against the
New York Jets, Warner posted 7 overall tackles, as well as a forced fumble which would be recovered by 49ers DL
Maliek Collins. With this forced fumble, Warner surpassed former 49ers LB
Ahmad Brooks for the second-most forced fumbles in franchise history. In Week 4 against the
New England Patriots, Warner returned an interception 45 yards for a touchdown and also became the first player in 49ers franchise history to record 10+ sacks and 10+ interceptions in his career. Warner was ranked 16th by his fellow players on the
NFL Top 100 Players of 2025.
2025 season On May 22, 2025, Warner signed a three-year, $63 million contract extension with the 49ers, making him the highest paid linebacker in the NFL. In Week 2, Warner recorded 11 tackles, one tackle for loss, a forced fumble and recovery in a 26–21 win over the
New Orleans Saints, earning NFC Defensive Player of the Week. In Week 6, in a 19-30 loss to the
Tampa Bay Buccaneers, Warner suffered a dislocated and broken ankle, which required him to get season-ending surgery. ==Career statistics==