Linkoping striker Blackstenius scored the only goal in the last-16 triumph against Canada and was on target once more in Rennes on Saturday to set up a meeting with Netherlands on Wednesday.
Sofia Jakobsson became the first player to strike against Germany at this year's World Cup when she cancelled out Lina Magull's opener in the 22nd minute.
Blackstenius completed the turnaround three minutes after the restart, earning Sweden a first win against Germany at a major tournament since 1995 – a run that included losses in the finals of Euro 2001, the 2003 World Cup and the 2016 Olympic Games.
Almuth Schult did well to keep out Jakobsson before Germany moved in front in the 16th minute. Magdalena Eriksson sloppily gave the ball straight to Sara Daebritz and the midfielder drove towards the box and fed Magull, who took a touch before volleying through Hedvig Lindahl's legs.
Jakobsson did not err when another opportunity came her way and she got Sweden back on level terms by slotting home after Marina Hegering failed to get her head on Linda Sembrant's clearance.
Germany lost left-back Carolin Simon to injury before half-time and fell behind soon after the restart when Schult could only parry Rolfo's excellent header straight to Blackstenius, who fired into the roof of the net.
Rolfo was shown a yellow card for a high foot on Magull in the 56th minute, meaning she will be suspended for Sweden's semi-final clash with Netherlands.
Dzsenifer Marozsan had been sent on for her first appearance since the opening win over China – in which she sustained a broken toe – at half-time.
And the Lyon midfielder's delivery led to a late VAR check for a possible penalty after Lindahl and Alexandra Popp collided. However, referee Stephanie Frappart's decision not to point to the spot was upheld.
Lena Oberdorf nodded a Marozsan free-kick that Lindahl flapped at wide with two minutes remaining, before Hegering failed to head Svenja Huth's stoppage-time cross on target from inside the six-yard box as Sweden clung on to end their dismal run against Germany.
