After being 2-0 down the Lions fought back to level and then won the match on penalties.
The turning point came at 3-3 during the shoot-out when Spain's Amaya, whose own goal gave Cameroon hope earlier, blazed over.
The next two penalties were scored but Wome strode up and his emphatic penalty gave Cameroon Olympic gold for the first time in any sport.
In a game brimming with incident, the Africans managed to haul themselves back from a dreadful start.
Perfect start for Spain
Spain struck after only 77 seconds when Xavi curled a flighted free kick into the net after Tamudo had been tripped on the edge of the box.
Things could have got worse for the Africans three minutes later when Jose Mari was brought down in the box by Nguimbat.
Angulo's tame penalty was well-saved low down to his right by 16-year-old Cameroon goalkeeper Carlos Idriss Kameni.
The respite was temporary. Spain increased their lead on the stroke of half-time when Gabri broke free on the edge of the area, shrugged off a defender and beat the keeper from about 10 metres.
After the break, Cameroon hauled themselves back into the match, beginning when Mboma's shot took a wicked deflection off Amaya and dribbled inside the right-hand post.
Buoyed by that lucky break, Cameroon continued to press and levelled when Samuel Eto'o controlled a cross from the left and coolly slotted home.
Spain were rattled, a mood that wasn't helped when they lost Gabri in the 71st minute with a reckless lunge that earned him a red card.
Spain down to nine men
Cameroon continued to dominate and were given a further boost in the last-minute of normal time when Mari was judged to have dived in the box and walked for a second bookable offence.
Extra-time nearly saw Spain grab a Golden Goal in the first minute but Chaptavilla's searing free-kick hit a post.
The Africans used their numerical advantage to dominate possession but could not break down the tenacious Spanish back line.
Samuel Eto'o managed to get the ball in the back of the net in the final minute of extra-time but was deemed to be off-side, a fact disputed by television replays.
It is the first gold medal Cameroon have ever won. Their only two other medals, a silver and bronze, were picked up in boxing.