The 25-year-old has beaten off strong competition, including from Leeds United talismanic midfielder Pablo Hernandez and Sheffield United defender Jack O’Connell.
Ajayi has been rewarded for an outstanding March, which has provided gloss to an excellent campaign for the Millers, which has seen him performing admirably as a holding midfielder and a central defender.
Latterly, the former Cardiff City player has shone in the middle of the park, while carving out a growing reputation as a goal-scoring midfielder of repute.
Ajayi reached to the top of the club’s scoring charts for the season with a haul of five goals in five games last month.
He netted a brace in the dramatic 3-2 win over Blackburn on March 2 and followed up with another double in the Millers’ 2-1 victory at QPR 11 days later which saw the club claim an overdue first away triumph at Championship level in almost three years.
Ajayi then struck in United’s 2-1 home loss to league leaders Norwich City.
Also nominated for the accolade was Canaries midfielder Emiliano Buendia.