Plouffe, who qualified for arbitration for the first time as a Super Two player, signed a one-year deal worth $2.35 million, while Duensing signed for $2 million and Swarzak signed for $935,000.
Plouffe, 27, hit .254/.309/.392 with 14 home runs and 52 RBIs in 129 games last season. He earned a raise of more than $1.8 million after making $520,000 last year.
Duensing, who turns 31 on Feb. 22, posted a 3.98 ERA with 56 strikeouts and 22 walks in 61 innings in his first full season as a reliever. The lefty received a raise of $700,000, as he earned $1.3 million in his first year of arbitration last year.
And Swarzak, 28, posted a 2.91 ERA while leading American League relievers in innings pitched with 96. The long reliever nearly doubled his $502,500 salary from last season.
It marks the eighth straight year the Twins avoided going to an arbitration hearing, as they last went to a hearing in 2006 with right-hander Kyle Lohse.
The three deals totaled $5.285 million, which brings the payroll to roughly $76 million for the 12 players officially under contract for 2014.