Marshall set a single-season Bears record with 118 receptions for 1,508 yards. Both were career highs for the seventh-year pro.
All four players were named to the Pro Bowl, as was defensive tackle Henry Melton.
There are two unanimous selections, Vikings running back Adrian Peterson and Texans defensive lineman J. J. Watt, as expected. Watt was one of 17 first-timers on the All-Pro roster, reflecting a 2012 season that was highlighted by new stars.
However, when it came to unanimity, it was also expected that Lions wide receiver Calvin Johnson, who broke Jerry Rice's single-season record for yards receiving, would have his name on every ballot.
But Johnson is one short of unanimous. He was not named by Tim Ryan, wh is an analyst for FOX Sports and Sirius Radio.
"Of course he had a great year and he is a great receiver, but I look at more than statistics and I thought a couple of other receivers had a better season, Brandon Marshall and A.J. Green," Ryan told The Sports Xchange.
"Johnson was targeted a lot and was often the only thing the Lions had going, but he also dropped a lot of passes and they did lose 12 games. I felt Marshall helped Chicago win games and Green helped Cincinnati win games. I think that is more important than statistics."
Johnson caught 122 passes for 1,964 yards, breaking Rice's record of 1,848 yards, but falling short of becoming the first wide receiver to total 2,000 yards in a season. However, despite those statistical prolifics, Johnson scored only five touchdowns while Marshall and Green had 11 each.
Marshall is alongside Johnson on the All-NFL first team, while Green is on the second team.
The easiest pick of the year was Peterson, surpassed all expectations except his own as he came back from major knee surgery on Dec. 31, 2011, and rushed for 2,097 yards, nine short of breaking the single season record by Eric Dickerson.
Watt, listed as a defensive end by his team, the league and on this All-Pro roster, played inside over the guard more often than not, which made his 20.5 sacks even more impressive, especially considering he was one of the very best run-stuffers as well.
Following are the list of the Associated Press first and second team selections and below that is an accounting of how many votes were cast for each player
WR: Calvin Johnson (Detroit Lions); Brandon Marshall (Chicago Bears).
TE: Tony Gonzalez (Atlanta Falcons).
OT: Duane Brown (Houston Texans); Ryan Clady (Denver Broncos).
OG: Jahri Evans (New Orleans Saints); Mike Iupati (San Francisco 49ers).
C: Max Unger (Seattle Seahawks).
QB: Peyton Manning (Denver Broncos).
RB: Adrian Peterson (Minnesota Vikings), unanimous; Marshawn Lynch (Seahawks).
FB: Vonta Leach (Baltimore Ravens).
K: Blair Walsh (Vikings).
KR: Jacoby Jones (Ravens).
DE: J.J. Watt, (Texans) unanimous; Cameron Wake (Miami Dolphins).
DT: Geno Atkins (Cincinnati Bengals); Vince Wilfork (New England Patriots).
OLB: Von Miller (Broncos); Aldon Smith (49ers).
ILB: Patrick Willis (49ers); NaVorro Bowman (49ers).
CB: Richard Sherman (Seahawks); Charles Tillman (Bears).
S: Earl Thomas (Seahawks); Dashon Goldson (49ers).
P: Andy Lee (49ers).
WR: A.J. Green (Bengals); Andre Johnson (Texans).
TE: Jason Witten (Dallas Cowboys).
OT: Joe Thomas (Cleveland Browns); Joe Staley (49ers).
OG: Marshal Yanda (Ravens); Logan Mankins (Patriots).
C: Maurkice Pouncey (Pittsburgh Steelers).
QB: Aaron Rodgers (Green Bay Packers).
RB: Alfred Morris (Washington Redskins); Jamaal Charles (Kansas City Chiefs).
FB: Jerome Felton (Vikings).
K: Phil Dawson (Browns).
KR: David Wilson (New York Giants).
DE: Justin Smith (49ers); Julius Peppers (Bears).
DT: Justin Smith (49ers); Ndamukong Suh (Lions); Haloti Ngata (Ravens).
OLB: Chad Greenway (Vikings); Ahmad Brooks (49ers); Clay Matthews, (Packers); and DeMarcus Ware (Cowboys).
ILB: Daryl Washington (Arizona Cardinals); London Fletcher (Redskins).
CB: Champ Bailey (Broncos); Tim Jennings (Bears).
S: Eric Weddle (San Diego Chargers); Jairus Byrd (Buffalo Bills).
P: Thomas Morstead (Saints).