It’s a significant milestone for a wedded couple – especially in Hollywood, where divorces happen so regularly they’re almost expected.
So what’s the secret to their long and seemingly happy marriage? Well, according to rumours based on the couple’s various interviews on the subject over the years, it’s that Will, 49, and Jada, 46, have an open marriage. That is, they allow each other to sleep with other people without it disturbing their bond.
It’s certainly an unusual approach – and an idea treated with intrigue and a hint of judgement by various media outlets and the public over the years. An open marriage makes for such a good story.
But is it actually true? Or have we all just been reading way too much into some possibly very simple statements on love and trust?
Well, the speculation didn’t come out of nowhere. Chatter seemingly started when Will Smith told The New York Post in 2005 that he could sleep with someone else, as long as he asks for permission first.
After commenting that his Hitch co-star Eva Mendes was "freaking gorgeous" he insisted it wasn't a comment his wife would mind hearing.
"Our perspective is, you don't avoid what's natural. You're going to be attracted to people.
"In our marriage vows, we didn't say 'forsaking all others'. The vow that we made was that you will never hear that I did something after the fact.
"If it came down to it, then one [spouse] can say to the other, 'Look, I need to have sex with somebody. I'm not going to if you don't approve of it — but please approve of it'."
Cue headlines like: Will Smith cheats on his wife - but asks for permission first.
But that's not exactly what the actor said. In fact, if you read that last quote back, he begins with "if it came down to it" - suggesting that that conversation hadn't ever occurred, and it's just his idea of what would happen if it did.
Yet, that buried the idea in the minds of pretty much everyone, and is why the parents to Jaden, 19, and Willow, 17, have been flagging questions about their so-called "open" marriage ever since.
In a video interview with HuffPostLive in April 2013, Jada seemed to confirm that status.
"I've always told Will, 'You can do whatever you want as long as you can look at yourself in the mirror and be OK,'" the Girls Trip actress said.
"Because at the end of the day, Will is his own man. I'm here as his partner, but he is his own man. He has to decide who he wants to be and that's not for me to do for him. Or vice versa."
Many took that as Jada saying she had given her husband, who she met in 1994 on the set of The Fresh Prince Of Bel Air and began dating while he was still married to his first wife Sheree Zampino, permission to sleep around.
But just days later she clarified in a Facebook post that they do not have an open relationship.
"Here is how I will change my statement...Will and I BOTH can do WHATEVER we want, because we TRUST each other to do so. This does NOT mean we have an open relationship...this means we have a GROWN one," she wrote within the lengthy post.
In that message, Jada explained that what she had meant is that she doesn't treat her husband like her property - and vice versa - and that he allows him freedom, because she trusts him not to hurt her. So in essence, she described a normal, healthy relationship without any jealousy or possessiveness.
And yet people weren't totally convinced that Will and Jada had just a normal, healthy relationship.
Which is why in 2015, while speaking with radio host Howard Stern, she addressed the "open marriage" question again, giving a very similar answer as in 2013.
This time though, she added, "Here is what’s real - I'm not the kind of woman that believes a man is not going to be attracted to other women.
"I'm just not that girl. It's just not realistic. And just because your man is attracted to another woman, does not mean he doesn't love you. That's not what it means. And it doesn't mean he's going to act on it. If your man can't really see another woman's beauty, how the hell is he going to see yours?"
And while promoting her film Girls Trip, Jada shut down suggestions they were "swingers" when asked what the most absurd thing she'd heard about herself was.
"The craziest rumour? That Will and I are swingers," she said on Watch What Happens Live with Andy Cohen. "That's the craziest one. It’s constant. And I’m like, 'Yo, I wish!'"
And if they're not fighting suggestions they sleep with other people, then they're reading "insider" reports about their impending divorce.
In 2015, Will decided to address them strongly via Facebook, writing "So, in the interest of redundant, repetitious, over & over-again-ness... Jada and I are...NOT GETTING A DIVORCE!!!!!!!!!!!!! I promise you all - if I ever decide to divorce my Queen - I SWEAR I'll tell you myself!"
Jada is also open talking about sex, even with her mum and her children on her Facebook show Red Table Talk. Post continues.
And in the three years that have passed it seems like nothing in their marriage has changed.
Will this week told Tidal's Rap Radar podcast that as far as he was concerned, their relationship would never end.
"We don't even say we're married anymore. We refer to ourselves as life partners, where you get into that space where you realise you are literally with somebody for the rest of your life," he said.
"There are no deal-breakers. There's nothing she could do - ever. Nothing that would break our relationship. She has my support till death and it feels so good to get to that space."
That, by all standards, romantic sentiment echoed comments his wife had made on US radio show Sway in the Morning last month.
"Here's the thing about Will and I are family. That is never going down. It's just not. Ever."
"We are family. Take out all that whole marriage/relationship crap, at the end of the day, Will and I are family."
"I am going to hold him down, doesn't matter. All that relationship and what people think ideas of a husband, partner and all that, man, whatever. At the end of the day, that is a man that can rely on me for the rest of his life, period."
And if that doesn't make you reassess your #couplegoals, Will's touching message on their anniversary in January probably will.
"Twenty years ago today we held hands and walked naively down that aisle," he wrote. "Here’s what I’ve learned since."
"Love is like gardening... I have learned to focus on HELPING you to BLOSSOM into what YOU want to be (into what you were born to be)... Rather than demanding that you become what my fragile ego needs you to be.
"I’ve learned to take pleasure in nourishing YOUR dreams... Rather than wrestling with you to fulfil my selfish needs and satiate my insecurities.
"I have learned that Love is listening. Love is giving. Love is freedom.
"Happy Anniversary, my queen! I am forever devoted to nurturing your deepest truth," he concluded.