Rajoy inherits a devastating economic downturn that has caused unemployment to swell to more than 21 percent, and comes as similar financial crises in European nations like Greece and Italy threaten to combine with Spain's woes and drag down the global economy.
As Rajoy, 56, begins forming Spain's next government, all eyes will be on whether the gray-bearded, bespectacled leader will finally unveil a clear political vision or continue to dodge efforts to pin him down.
In his victory speech, Rajoy said he has no miraculous solutions to jolt Spain out of its economic misery, but promised that the country "will stop being part of the problem and become part of the solution" after he takes power in December.
"When you do things right, you get results," said Rajoy, whose party won 44.6 percent of the vote compared to 28.7 percent for the Socialists, with 99.6 percent of the vote counted.
Many see him as a the perfect caricature of his native region -- Galicia. The people of the misty and rainy northwestern region are legendary for pokerfaced obscurity. According to a Spanish saying, when you meet a Galician on the stairs you can never tell if he's going up or down.
"He is a Galician. They say things but you have to read between the lines," said Rodrigo Herrero, 48, a villa caretaker.
"He's not spontaneous or extroverted like other politicians," added Herrero. "He lacks that friendliness and touch of charm."
Others says there is a hidden side.
"He's a master because he achieves his aims without apparently doing anything," Xavier Pomes, a Catalan politician and friend of Rajoy, told El Pais, Spain's leading newspaper.
"He's sensible, frank. Some see him as indolent and indecisive but in reality he's reflexive," said Pomes.
But true to his cagey character, Rajoy has so far made little known of his plans. And with bond interest rates soaring and stock markets jittery, he is not likely to have any more time to dawdle or fudge.
In a lengthy interview in El Pais on Thursday, Rajoy said that barring pensions, "cuts will have to be made wherever they can." But the paper pointed out that he "maintained his ambiguity on what sacrifices Spaniards will face."
Eurasia Group analyst Antonio Barroso expects Rajoy to initially go for a "shock and awe strategy" with "quick policy changes in an effort to impress markets and his European partners, and boost Spanish credibility."
That would also dispel questions about his own credibility.
Rajoy, a property registrar by training, held four ministerial portfolios
-- among them education and interior -- in the governments of Jose Maria Aznar between 1996 and 2004. But being hand-picked as party leader in 2003 by Aznar set Rajoy up for years to accusations that he was never actually elected by those in his party, a smear that weakened his attempts to shake himself free of Aznar's shadow.
Sunday's ballot was third-time lucky for Rajoy. He lost general elections in 2004 and 2008 against Jose Luis Rodriguez Zapatero, who is now deeply unpopular and did not seek re-election this time. In many ways, it's a tribute to his dogged determination to survive.
In 2004, Rajoy was also strongly tipped to win. But he lost amid voter outrage over the Madrid terror bombings by Islamic militants three days before the election. The massacre killed 191 people. Rajoy and his party had initially blamed Basque separatists and continued to do so even as evidence of Islamic involvement emerged.
