Walsh played college football for the Georgia Bulldogs and was selected by the Vikings in the sixth round of the 2012 NFL draft.

Walsh attended Cardinal Gibbons High School in Fort Lauderdale, Florida, and played football for coach Michael Morill as their punter and placekicker.

On December 16, Walsh passed Randy Moss for the Vikings' franchise record in points scored by a rookie (119).

[6] His 5 kicks also tied an NFL record for most field goals of 37 yards or more in a single game, 5, which only Chris Boniol equaled for the Cowboys in 1996 and Scott Norwood in 1988.

The next week in a game against the Houston Texans on December 23, 2012, Walsh completed a 56-yard attempt, setting the NFL record for field goals over 50 yards in a season with his ninth 50+ yarder.

His final regular season field goal allowed the Vikings to beat the Green Bay Packers 37–34 and earn a playoff berth.

[10] Walsh broke the record three weeks later against the Pittsburgh Steelers in London, England with his twelfth straight 50+ yard field goal.

On November 24 against the Green Bay Packers Walsh hit four of four field goals and had five touchbacks off kickoffs; he was named NFC special teams player of the week.

For his efforts after scoring 19 points in Minnesota's 49–17 win over the Giants, Walsh was named NFC Special Teams Player of the Week.

He missed an extra point in a 26–20 Week 10 loss to the Washington Redskins which led to his release from the Vikings on November 15, 2016.

[17] He gained national attention during his second preseason game where the Seahawks beat the Minnesota Vikings, his former team, 20–13.

[18] On September 10, 2017, in the season opening 17–9 loss to the Green Bay Packers, Walsh converted three field goals in his Seahawks debut.

On December 31, 2017, as the Seahawks were playing for a spot in the playoffs against the Arizona Cardinals, Walsh made a 49-yard field goal early in the fourth quarter.

Due to Walsh's unsatisfactory performance in the 2017 NFL season, the Seahawks signed former Jacksonville Jaguars place kicker Jason Myers.