Johnson and Allen each received 49 out of a possible 50 votes from a national panel of 50 media members.
Quarterback Aaron Rodgers of the defending Super Bowl champion Green Bay Packers earned 47 1/2 votes to easily outdistance New Orleans Saints QB Drew Brees, who got the other 2 1/2 votes.
Johnson led the Lions to their first playoff berth since 1999, hauling in 16 touchdown passes and leading the league with 1,681 yards.
Allen was one of the few bright spots in a dismal season for the Vikings, registering a league-high 22 sacks to fall one-half sack short of the NFL record.
Rodgers has guided the Packers to a 15-1 mark, throwing for 45 touchdowns against only six interceptions. Green Bay won its first 14 games before its bid for a perfect season ended at Kansas City.
Running backs Maurice Jones-Drew of the Jacksonville Jaguars and LeSean McCoy of the Philadelphia Eagles joined fullback Vonta Leach of the Baltimore Ravens in the backfield.
Jones-Drew led the league in rushing with 1,606 yards and McCoy scored an NFL-best 20 touchdowns.
Filling out the receiving corps were a pair of players from the New England Patriots, wideout Wes Welker and tight end Rob Gronkowski. Welker led the league with 122 catches and Gronkowski had 17 touchdowns while setting a league mark with 1,327 receiving yards.
Center Maurkice Pouncey of Pittsburgh anchored the offense line. He was flanked by both New Orleans guards in Carl Nicks and Jahri Evans as well as tackles Joe Thomas of Cleveland and Jason Peters of Philadelphia.
Joining Allen along the defensive front were Jason Pierre-Paul of the New York Giants, Baltimore's Haloti Ngata and San Francisco's Justin Smith.
Ravens linebacker Terrell Suggs, who earned 47 votes, headed a five-player unit that includes Dallas' DeMarcus Ware, Kansas City's Derrick Johnson and 49ers teammates Patrick Willis and NaVorro Bowman.
New York Jets cornerback Darrelle Revis was the second-leading vote-getter on defense with 48. He was named opposite Green Bay's Charles Woodson.
Pittsburgh's Troy Polamalu and San Diego's Eric Weddle were the selections at safety.
Kicker David Akers and punter Andy Lee of San Francisco made the team, as did Arizona's Patrick Peterson, who was the kick returner and only rookie on the squad.