Passing up the opportunity to voice a character in a Disney project is something few actors would consider. But Tiffany Boone, who voices Sarabi in the upcoming animated adventure "Mufasa: The Lion King," had second thoughts when she discovered months into the audition process that the film was a musical.

“In the last audition, they said, ‘We need her to sing,’ and I was like, ‘Excuse me? Nobody told me this was required, because I probably would’ve said no from the start,’” Boone tells BET. “They wanted me to sing a song from "The Princess and the Frog," and I thought, ‘You want me to sing something Anika [Noni Rose] sang? Okay, sure.’ But I got a vocal coach, did the audition, and later, while I was at a store shopping for a mattress, I got the call [that I got the role]. I just started crying — right there on the mattress.”

It was a validating moment for Boone, who had given up on voiceover auditions after years of rejection. “I wasn’t booking them, no matter how hard I tried,” she says. Landing the role of Sarabi, however, came with another wave of anxiety.

“I didn’t even know I was auditioning for Sarabi,” Boone recalls about the future queen of the Pride Lands and Simba’s [Donald Glover] mother. “They called her by a different name, so when I got that call at the mattress store, I asked, ‘Who is she?’ They said, ‘Sarabi,’ and I thought, ‘Wait, Sarabi? What are you talking about?’ That’s a lot of pressure. That’s Beyoncé’s mother-in-law!”

Determined to rise to the challenge, Boone approached her preparation for Barry Jenkins’ animated prequel as she would a live-action role. “Once I realized I had to sing, I thought, ‘We’re going to the gym.’ Except my gym was a music studio, and my trainer was a vocal coach,” she explains. Boone worked with her coach for nearly a year before Disney and Lin-Manuel Miranda, the film’s composer, joined the process. Soon after, she found herself practicing music four to five times a week, learning to use her voice and conquering a long-held fear of singing in front of others.

“I had a phobia of singing because my mom once told me people were laughing at me during a talent show in middle school,” Boone shares. “I had to relearn how to love singing, the way I did as a child.”

Boone’s efforts paid off. She performs two songs on the movie’s soundtrack: “We Go Together,” an up-tempo ensemble number featuring co-stars Aaron Pierre (Mufasa), Kelvin Harrison Jr. (Taka, who later becomes Scar), Preston Nyman (Zazu), and Kagiso Lediga (young Rafiki), and “Tell Me It’s You,” a duet with Pierre capturing Sarabi and Mufasa’s budding romance.

But Boone’s preparation was nearly derailed on the morning of her recording session when she woke up with a scratchy throat. “I thought, ‘What are the chances?’” she says. “I begged to reschedule, but they said, ‘Just come in and let’s try.’”

To her surprise, the session went smoothly. “Towards the end, Lin-Manuel Miranda popped up on Zoom and said, ‘Let’s do the song again.’ I sang it, and he literally said, ‘That was perfect.’ I thought I’d need a few days to finish, but I was wrapped shortly after that.

“After a year of sleepless nights and fear, it ended up being a really fun day,” Boone adds.

This year has been equally rewarding for Boone’s acting career. Earlier this spring, she starred in "The Big Cigar," Apple TV+’s heist series about Huey P. Newton (André Holland), in which she played Newton’s first wife, Gwen Fontaine.

“I’ve had the chance to bring these incredible women to life,” Boone says of her roles in two male-centered projects. “Most people didn’t know who Gwen Fontaine was, yet she was so important. Similarly, Sarabi was integral to the original "Lion King," but we didn’t know much about her. To explore these women, show their strength, and highlight the women behind the men — because we all know we’re the ones who do it — has been a real blessing.”

Boone admits her journey has been unexpected. “When [Mufasa] landed on my desk, I never thought I’d book it, but I couldn’t say no to the opportunity,” she says. “If someone had told me I’d be in "The Lion King" with Beyoncé and Blue Ivy, I wouldn’t have believed them. But pushing past your fears? This is the kind of magic that can happen.”

"Mufasa: The Lion King" opens in theaters on December 20th.