The trio, who were all in the 2nd Royal Regiment of Fusilliers have all been killed in Afghanistan over the last few days.
City's Commercial Director Nathan Kosky told the club website: "We are as shocked as everyone else to hear of the deaths of the three local soldiers in Afghanistan and the thoughts of everyone at the Ricoh go out to their families.
"We are planning to pay a mark of respect to them on Saturday when we play Swansea City. There will be photo tribute on our scoreboard and the team will wear black armbands."