The Premier League leaders are the only club to have two players nominated for the end-of-season accolade.
Liverpool's Philippe Coutinho, Manchester United keeper David de Gea, Tottenham Hotspur striker Harry Kane and Arsenal forward Alexis Sanchez are also on the shortlist.
Brazilian-born Spain striker Costa is the league's top scorer with 19 goals, having joined Jose Mourinho's side from Atletico Madrid in the close season.
Belgian international Hazard has flourished in the playmaker role, helping Chelsea open a seven-point gap at the top of the table with a game in hand and seven matches still to play.
Hazard also makes the Young Player of the Year shortlist where he is joined by Coutinho, De Gea and Kane as well as his Chelsea team mate and Belgium goalkeeper Thibaut Courtois.
Liverpool forward Raheem Sterling, who has made headlines after footage emerged of the England international apparently taking nitrous oxide as well as for his contract standoff at the Merseyside club, is also up for the Young Player of the Year award. – Reuters
Original source: Chelsea duo up for PFA award