This Is Us” star Mandy Moore successfully transitioned from a teenage pop star to an adult who juggles singing, acting and, soon enough, producing professionally. On March 25 she is being celebrated for her achievements with a star on the Hollywood Walk of Fame, an honor she calls “tremendously humbling.”

“I feel like I’m operating at my best now. I know what I want; I know how to ask for it; I know how to not settle until I get that,” Moore says. “I’m better at stepping up to the plate and acknowledging the value I bring to the plate. I guess that just only comes with the wisdom and clarity of time and age.”

The singer-turned-actress got her first taste of fame at the turn of the century when her debut single “Candy” hit the Billboard Hot 100 charts. Two years later she was dipping her toes in acting waters with such films as “The Princess Diaries,” and soon enough earning starring roles in features including “A Walk to Remember” and “Chasing Liberty.”

Moore credits the fact that she didn’t have “tremendous success” as a pop star — that debut single peaked at No. 41 on Billboard, for example — with allowing her to cross over so easily into other media.

“I feel like it is inherently more difficult if you are a wild, worldwide success in one arena for people to take you as seriously doing something totally different,” she says. “I wasn’t maybe as successful as my contemporaries [and] it made me be more of a chameleon.”

For her role as Jamie Sullivan in 2002’s “A Walk to Remember,” Moore dyed her hair brown, which she thinks helped “shift the public consciousness” about who she was and what she could do. It was the first, most simple way she immersed herself into a role, but such transformation proved to become an integral part of her process.

Over the years Moore moved among music, film and television. For the latter, she appeared on pop-culture phenomenon series including “Entourage,” “Scrubs” and “Grey’s Anatomy” before booking the role of matriarch Rebecca Pearson on NBC family drama “This Is Us.” There, she plays Rebecca over several decades of the character’s life, from 16 to 60-something.

“Mandy didn’t know we were going to be aging her when she took the part,” says “This Is Us” creator Dan Fogelman, who also produced “Tangled,” in which Moore voiced Rapunzel. “A bit before we went into production on the series, I met with her and told her what I was thinking. The promise made was that if we didn’t buy it 100% we’d bail on it and cast an older Rebecca. … I still have the first photo still they took of Old Rebecca, I keep it in a file on my computer under ‘This Is Us’ for stuff that I didn’t want to lose. It’s the first thing in the file.”

Although Moore admits that initially she was “terrified” by the challenge, after a number of makeup tests she trusted the team behind the show. Intense homework, including working with a “physicality coach” also helped her build up the muscles needed to portray the character at all stages of her life.

In the first season of “This Is Us,” Moore began thinking about the eldest version of her character’s energy as a “lamp with the lampshade off and the light just going directly to the ceiling,” she says. “There’s something sort of rigid and very strong about it.”

Imagining that posture, from a woman who may be “a little quieter” but also “a little steadier and confident and comfortable in her skin,” along with putting on the wig and right clothing makes Moore slip immediately into character.

Fogelman admits that Moore has influenced the evolution of the character in many ways, starting with the fact that she once had dreams of being a singer. But he also ended up including an audition-only monologue, in which Rebecca tells a drunk Jack that he needs to step up and be a better parent, in a later episode of the series, because Moore was so moving when she read it.

“Mandy is so accessible and so winning, she could have easily allowed herself to be pigeonholed as pop star-turned-romcom-sweetheart, but she’s a monster heavyweight actor who I’d confidently put toe-to-toe with the biggest and baddest out there,” he says. “She has never blinked whenever we’ve thrown anything challenging at her, and now people are seeing her as such. The lesson: if you judge a book by its cover, you risk missing out on a really great story.”

Three seasons into “This Is Us,” becoming Rebecca feels like “slipping on a pair of old shoes,” Moore says. Still, she says she finds herself challenged by the material she is given in each week’s scripts as she discovers new pieces of her character’s past as they go on.

“I play this woman who is flawed, and I get to play her when she’s more idealistic and optimistic and hungry for a career; I play her as a sort of burdened mother; I play her as grief-stricken because she’s lost her husband,” she says. “This is the dream job. This what you wait those 20 years for in a career.”

The summer after Moore’s first season on “This Is Us” her independent film “47 Meters Down” finally opened in theaters. The movie had been pitched to her as “Do you want to go underwater for six weeks?” during a time when she was going through an “acrimonious divorce” (from musician Ryan Adams, about whom Moore spoke out earlier this year after harassment and abuse allegations rose against him. Moore had no additional comment about him at this time). “That sounds like the weirdest, craziest challenge; sign me up,” she recalls saying. “47 Meters Down” was then shot two years ahead of booking her starring role on NBC, and Moore admits she had “no idea [if] it was ever going to come out.” But Byron Allen and his Entertainment Studios venture came in and offered $3 million to original distributor Dimension Films.

Allen previously told Variety he knew releasing a shark movie in the summer “never fails,” and a combination of timing and Moore’s rising profile undoubtedly helped push the film to the top of the list of highest-grossing independent films in 2017, bringing in almost $45 million at the box office.

A sequel is now planned, though Moore has set her sights on bigger things on land instead. In September, she signed a two-year production deal with 20th Century Fox Television to develop and produce new series.

Moore plans to use the few months of her “This Is Us” hiatus to “find projects that are for women, by women” that she can work on behind the scenes. “I would love to find something with a musical leaning,” she says. “I’m obsessed with current events and politics. I would love to find those stories told through a female lens.”

And Moore is also looking forward to getting back into the recording studio to make some new music.

“This is the season of my life I think I’m most proud of. The choices I’ve made, the woman I strive to be, the people I’m lucky to be surrounded with both personally and professionally, this is a chapter in my life I’m really savoring and trying to hold onto and build upon, but it’s taken a lot of work to get here.”