Contrary to popular belief, most pop stars don't wear sunglasses indoors and even fewer keep them on for interviews. So it's disconcerting to meet California soul singer Aloe Blacc in a lobby at Radio 1 and face a pair of expensive mirrored lenses. Perhaps it's just that his eyes hurt, because this celebrity affectation is misleading. If you didn't know who Blacc was, you'd assume he was successful at something but not necessarily music. He dresses like a fashion designer, in a hip country gent ensemble so spotless that sitting next to him makes me feel like Worzel Gummidge; he talks with the persuasive eloquence of a high-flying thinktank wonk; and he radiates unflappable self-assurance.

The 35-year-old has every reason to feel confident. His hard-times soul jam I Need a Dollar caught the recessionary mood in 2010 and made him a gold-selling star in Europe. Then Wake Me Up, recorded with EDM producer Avicii, became one of last year's most unavoidable singles, reaching No 1 in 22 countries. Even though he was denied a featured artist credit ("that's just business," he says with a flicker of irritation) and it sounded more like Mumford & Sons with glowsticks than his usual material, Wake Me Up introduced his voice to millions. Now there's The Man, a swaggering can-do anthem that has become his first US hit, and is set to take the UK No 1 spot on Sunday. Lift Your Spirit, his third solo album and his first for Interscope, is emphatic, optimistic folk-soul reminiscent of Bill Withers and Stevie Wonder. He is yet to put a foot wrong.

On the surface, it seems like a classic case of ambition paying off after years of struggle. Blacc, whose real name is the splendid Egbert Nathaniel Dawkins III, formed the underground hip-hop duo Emanon in his teens (he chose Aloe because his style was "smooth like lotion"), switched to singing a decade ago, and only broke through in his 30s. Except, as Blacc admits, there wasn't much struggle or ambition involved. "Music was a hobby," he says cheerfully. "There wasn't that urgency of feeling, like I needed to make it in the music industry. I'm glad I had a decade or more of doing it for fun so I know what it feels like and I don't do it for any other reason."

In fact, I Need a Dollar was more a genre exercise, inspired by hearing field recordings of chain-gang songs, than a howl of penury. He wrote it in 2005 while living in a squat after losing his job, but that job happened to be at multinational accounting firm Ernst & Young, where he helped children's hospitals improve services. ("It took too long for there to be a president to finally make a healthcare system that made sense for citizens," says this Obamacare fan.) So he wasn't exactly on skid row. "It wasn't a place of despair. I could go back to school and get a PhD. I could get another job in corporate America. There was no fear of starving."

It's rare to hear a musician puncture his own mystique with boasts about his real-world CV, but perhaps Blacc is so frank because his parents really did follow a rags-to-riches path. Their childhoods in Panama were grindingly poor but by the time Blacc was born in suburban Orange County, California, in 1979, his father was a rising star in the US Army. "He was a strategy guy," Blacc says proudly. "I think he was too smart for them to risk in combat. I lucked out because the cycle of struggle usually continues."

Blacc was a straight-A student who won a scholarship to the University of Southern California to study communications and linguistic psychology. "It's kind of a nerdy interest," he says. "It helps me to continue whetting my blade as a thinker. I don't play the new app of the week on my phone, I play with words. I put them together in little puzzles and see how they make me feel and then do this projection puzzle to the rest of the world and ask how they will make other people feel."

Again, his candour is unusual. Most songwriters prefer to cite raw instinct, divine inspiration or dumb luck, but Blacc has an almost academic curiosity about how music works. When he describes the disastrous debut of Wake Me Up at Miami's Ultra festival, where ravers were nonplussed by the appearance of a soul singer and a guitarist, he sounds like an anthropologist conducting fieldwork in strange climes. "The audience is largely on drugs," he says. "So they're expecting to have the kind of music that accommodates the sensations they're feeling. I can understand why people were upset."

Was he shaken by the reaction? Not at all, he says with a serene smile. "If it's not going to take food out of my mouth or shelter from my head or threaten my body physically, it's not a big deal."

He started the Wake Me Up lyric, about being so stunned by good fortune that you think you're dreaming, while being flown first-class to a watch-makers' conference in Geneva. I ask him why he thinks it resonated and he already has a theory. "It's instant nostalgia. The other side of the coin is instant projection into the future. If you're a teenager you're thinking: 'This is my future.' If you're a parent you're thinking: 'This is my adolescent years.'"

Blacc confesses he's a "nostalgia buff". He appeals to people who wonder why they don't make soul singers like they used to because he's one of those people. He moved away from hip-hop a decade ago because "I didn't feel at home any more. It became very violent and misogynistic. It wasn't fun anymore, not like the Tribe Called Quest/De La Soul days."

In the video for The Man he dresses like Marvin Gaye on the cover of What's Going On and Martin Luther King on the march from Selma to Montgomery. He thinks he knows why socially conscious lyrics are rarer now. "The industry is choosing artists with no perspective because people with no perspective can be manipulated and used at the whim of the business people. Bono's doing it but he's not a contemporary young artist. He comes from an era of people who sing songs about change and want to engage."

Blacc is a pragmatist, not a radical. He has chosen his causes carefully – malaria relief in Africa, food distribution in Los Angeles – and has no qualms about Bono-style realpolitik. "If you don't try to woo the people in power then you're always going to be an outsider and they're going to block you. Yeah, I'm going to have to shake hands everywhere in order to get what I want done."

Of course, liberal activist musicians come in for a lot of flak, from the left and the right. Is he ready for that? "We're in a culture of flak," he says evenly. "We live in a cynical time. You can see it when you go on YouTube and there's 75% negative comments. It's just a disease of our time. That's why I wrote a song called Love is the Answer. Love is the answer, not hate or cynicism or anonymous denigration: 'Oh, I can hide behind this computer screen and be as foul and ignorant as I want.'"

So does he read the comments below his own videos? "I read every comment," he says, smiling. "Coming from a background of studying communications and linguistics, I know what it's worth. It doesn't mean anything to me and I hope it doesn't mean anything to them, otherwise we're looking at an era of very depressed and dark and dismal people."

Blacc can talk with authority about healthcare, education and income equality but Lift Your Spirit is a lot less politically explicit than 2010's Good Things, thanks to his dad. "He heard the last album and said: 'Yo, you have to make happier songs. Sing some love songs. Girls want love songs.' And I thought: 'Yeah, you're right.' Why preach to the choir? I've learned that there's no reason in screaming revolution and pointing the finger. The most important thing to do is preach the positive." I hope it doesn't make me a horrible cynic to note that this upbeat approach is also more commercial.

Blacc is what is known in tech circles as a "solutionist". Whether the challenge is a hit single that can sell headphones or getting fresh fruit and vegetables to deprived urban neighbourhoods, he believes he's smart enough to find the answer. He may overreach one day but for now you wouldn't bet against him. Like his father, Aloe Blacc is a strategy guy.