With Lionesses manager Sarina Wiegman back on the touchline after returning a negative COVID-19 test, Esther Gonzalez and Ella Toone struck for their nations in normal time before a Georgia Stanway thunderbolt sent England into the semi-finals.
The contest on the South Coast started in lively and scrappy fashion, with Spain not allowing England a moment to get comfortable in possession and challenges flying in left right and centre.
Spain started to turn the screw approaching the 20-minute mark, outmuscling England aerially and getting the ball into the box, albeit without really troubling Mary Earps.
However, it was England who first had the ball in the back of the net after 37 minutes, as Ellen White smashed home following a goalmouth scramble from Lauren Hemp's free kick. The lineswoman immediately raised her flag for offside, though, and VAR upheld her decision.
Neither side would find the breakthrough in the opening 45 minutes, and the opening stages of the second half saw a protestor try to tie themselves to the post before the stewards prevented them from doing so.
Wiegman's crop would show a bit more bite in the second half, but Spain would draw first blood in the 54th minute, as substitute Athenea del Castillo skipped past the challenge of Rachel Daly on the right-hand side before finding Gonzalez, who fired into the bottom corner.
England would be controversially denied a penalty on the hour mark when Hemp went down following contact from Ona Batlle, and Spain went close to an unorthodox second moments later, as Earps had to be alert to keep out Del Castillo's cross-cum-shot.
The cavalry of Toone, Alessia Russo and Chloe Kelly would arrive to try to restore parity for England, and Daly would attempt to make up for her earlier error with a long-range effort that only found the grateful gloves of Sandra Panos, as England finally had a shot on target after 69 minutes.
A flurry of blocked Lionesses efforts 15 minutes from time ended with Hemp firing over the bar as the hosts pressed for an equaliser, but Jorge Vilda's side would threaten to double their lead every time they went forward.
England would finally be rewarded for their persistence in the 84th minute, as Russo outmuscled Irene Paredes and headed the ball down for Manchester United teammate Toone to fire home on the volley from a few yards out and force extra time.
The Amex had already exploded for Toone's equaliser, but the crowd were treated to an even more special goal in the 96th minute, as Spain's defenders backed off and allowed an onrushing Stanway to unleash a 20-yard rocket into the top corner.
Late Spain pressure would come to nothing as jubilant scenes followed for those in white, with England now preparing for a semi-final against either Sweden or Belgium at Bramall Lane next Tuesday.