Michal Pospisil grabbed Hearts' winner as last year's runners-up started their Scottish Premier League campaign with a victory at East End Park.
Roman Bednar opened the scoring against Dunfermline
Roman Bednar slipped in the opener for the visitors following a cross from his fellow Czech striker.
Former Hearts midfielder Stephen Simmons bundled home the equaliser following a corner.
But Pospisil pounced after Bruno Aguiar struck the crossbar and the Pars' Andy Tod was sent off for violent conduct.
Pospisal had come into the side along with midfielders Saulius Mikoliunas and Julien Brellier as Hearts made three changes to the side that won in the Champions League in midweek.
Striker Edgaras Jankauskas was suspended, while Ibrahim Tall dropped to the bench along with Deividas Cesnauskis.
Dunfermline included five new signings, including striker Noel Whelan, who joined on Friday, and defender Souleymane Bamba, whose international clearance arrived on time.
But Whelan's debut lasted no more than five minutes, with the striker picking up an injury to be replaced with Tod.
Dunfermline were looking the more likely to grab the opener with the strength and pace of winger Freddie Daquin proving a handful for the visiting defence.
But, in the 15th minute, Bednar latched on to a cross and poked the ball past Roddy McKenzie from six yards out as the new Pars goalkeeper was caught out of position.
Dunfermline rallied, but Hearts had the greater quality and McKenzie did well to beat away midfielder Aguiar's snap-shot from 30 yards.
Hearts started the second-half well and a half-volley from Neil McCann struck the crossbar.
Dunfermline equalised against the run of play when Simmons forced the ball home after a corner.
Hearts were stunned back into action and Bednar flashed a header over.
Daquin squandered a chance to give Dunfermline the lead when he was through on Craig Gordon, but the goalkeeper forced him wide and the chance was lost.
New signing Calum Woods tested Gordon with a free-kick that was fisted clear by the goalkeeper.
Pospisil pounced when Aguiar's free-kick struck the bar and the Czech striker bundled the ball home on the rebound.
Tod received his marching orders after confronting Brellier, who he had accused of play-acting following a tackle.
And Pars assistant Craig Robertson was sent to the stand for the strength of his own protests on the touchline.
Dunfermline: McKenzie, Shields, Woods (Owen Morrison 81), Scott Wilson, Bamba, McGuire, Simmons, Mason, Muirhead, Whelan (Tod 6), Daquin (Burchill 72).
Subs Not Used: McCunnie, Craig Wilson, Devries, Phinn.
Sent Off: Tod (80).
Booked: Tod, Muirhead, McGuire, Bamba, Simmons.
Goal: Simmons 62.
Hearts: Gordon, Neilson, Fyssas, Berra, Pressley, Brellier (Tall 86), Aguiar, Mikoliunas, McCann (Cesnauskis 70), Pospisil, Bednar (Makela 83).
Subs Not Used: Banks, Mole, Neill, Driver.
Booked: Aguiar, Bednar, Brellier.
Goals: Bednar 15, Pospisil 78.
Ref: B Winter