The Spaniards, who won their first European title in Poland in 2009, overpowered tournament upstarts Macedonia 92-80 while France, looking for their maiden major championship crown, beat Russia 79-71.
Macedonia, who went into the 24-team tournament in Lithuania as one of the underdogs, were worthy opponents but Spain broke them down thanks to a breathtaking performance by point guard Juan Carlos Navarro and centre Pau Gasol.
Navarro scored a game-high 35 points and led the way when the Spaniards overcame a 45-44 halftime deficit to lead 71-62 at the end of the third quarter.
Los Angeles Lakers centre Gasol added 22 points and 17 rebounds while his younger brother Marc and Congolese-born forward Serge Ibaka chipped in with 11 points each.
American-born point guard Lester Bo McCalebb, the driving force behind Macedonia's success in the tournament, scored 25 points for the former Yugoslav republic and Pero Antic added 17 points and nine rebounds.
"We have reached our initial objective to qualify for the Olympics. It was a tough match today and Macedonia have had a magnificent tournament," Navarro told Spanish television.
"We are very pleased to have reached the final and I am delighted to have helped the team. There are opportunities that you can't allow to escape and now we will go all out for the title."
Russia reached the last four with an impressive 9-0 record but were powerless against a more athletic French team who kept pulling away as guard Tony Parker shone again.
Parker, a triple NBA champion with the San Antonio Spurs, led all scorers with 22 points while shooting guard Nicolas Batum added 19 points along with seven rebounds and four assists.
Utah Jazz forward Andrei Kirilenko stood out for 2007 winners Russia with 21 points.
France go into the final confident they can do better than their 96-69 defeat by Spain in the second group stage.
"We played a solid game today and we'll have to play another solid game on Sunday. I am proud of my team mates and it's a great victory," Parker told Canal Plus television.
Earlier on Friday, Greece beat Serbia 87-77 and now meet Lithuania in a fifth and sixth place playoff match on Saturday.