He played college football for the Notre Dame Fighting Irish and was signed by the Cincinnati Bengals as an undrafted free agent in 1987.

Carney was also a member of the Tampa Bay Buccaneers, San Diego Chargers, New Orleans Saints, Los Angeles Rams, Jacksonville Jaguars, Kansas City Chiefs, and New York Giants.

Carney attended Cardinal Newman High School in West Palm Beach, Florida, and lettered in football.

Carney was re-signed by the Chargers during the 1990 season, appearing in 12 games for the team and converting 19 of 21 field goal attempts.

As time expired, the Saints continued to lateral the ball around until wide receiver Jerome Pathon eventually scored a touchdown in what became known as the River City Relay.

He then appeared on the cover of Sports Illustrated with quarterback Aaron Brooks on September 19, 2005, as the city celebrated this victory.

Following Week 1 of the 2007 NFL season, Carney signed with the Jacksonville Jaguars replacing injured placekicker Josh Scobee.

On November 26, 2007, the Kansas City Star reported that the Kansas City Chiefs would sign Carney after holding tryouts to replace Dave Rayner – making Carney the fourth placekicker to play for the Chiefs within a one-year period, following Lawrence Tynes, Justin Medlock and Rayner.

On August 30, 2008, Carney signed with the New York Giants to fill in while Tynes recovered from a knee injury sustained in training camp.

[3] After a near perfect season (35-for-38 on field goal attempts with two blocked),[4] Carney was chosen as the starting kicker for the NFC for the 2009 Pro Bowl.

On October 3, 2010, he kicked three field goals in a Saints win against the Carolina Panthers, and became the third oldest player to play in an NFL game (behind only George Blanda and Morten Andersen).

John runs a pre-season kicking training camp in San Diego for professional kickers called "The Launching Pad".