During the pre-Broadway run of “Good Night, Oscar” at the Goodman Theater in Chicago, the actress Emily Bergl was known to the staff as “the lady in the Dress.”

As June, the wife of the troubled raconteur-pianist Oscar Levant, Bergl wears a floral dress and matching chartreuse coat. The dress radiates the energy of a Jackson Pollock canvas — black and daffodil-yellow on shimmering silver brocade, hand-painted to generate the perfect luster for the stage. It stands out in that show’s sea of impeccable suits.

Bergl calls it the Dress.

“I’m not discrediting my performance in ‘Good Night, Oscar’ when I say that the Dress does half the work,” she said.

When Bergl first met the man behind the Dress, the costume designer Emilio Sosa, he told her, “June Levant’s clothes are armor.”

“I knew right away that he understood the character completely, and that I was in good hands,” she said.

In a recent phone interview, Sosa said: “Listening to actors is 95 percent of my design. You need to have your actors actively involved in the costume they’re going to wear.”

This season, Sosa has dressed 94 actors for five Broadway productions in 450 costumes. He has earned two Tony nominations for his costume design, for “Good Night, Oscar” and “Ain’t No Mo’,” a satire on contemporary Black America. He also designed costumes for the Neil Diamond bio-musical “A Beautiful Noise,” and the revivals of “1776” and “Sweeney Todd.”

It has been a dizzying blur of looks, from sensible suits to sequins, from American colonial-era dress to Crayola-colored camp.

At his busiest, Sosa found himself working on three shows at once, averaging three hours’ sleep a night. He follows a maxim he picked up early on from his mentor, Geoffrey Holder, “The Wiz” director and multifaceted cultural figure: “‘Say ‘yes’ to everything — then figure out how to make it work.’”

Sosa, 57, describes himself — tongue firmly in cheek, he wants to be clear — as an overnight sensation 30 years in the making. Sosa made his Broadway debut in 2002 with Suzan-Lori Parks’s “Topdog/Underdog.” His second Broadway show, for which he earned his first Tony nomination, was “The Gershwins’ Porgy and Bess” in 2012.

Sosa was also a contestant on the reality TV competition “Project Runway,” in 2010 and 2012, an experience he credits with building the confidence that allowed him to present himself and his designs.

In between, there has been a lot of “hustling, struggling, and trying to earn a living” including plenty of work in regional theater. “I was a broken kid with a tough upbringing,” Sosa said. “But I figured out, in the arts, no one could beat me. So I developed that. That’s where the drive comes from.”

If there’s something Sosa’s diverse projects have in common, it might be his enthusiastic embrace of color. “In my culture, as a Latino, we’re not afraid of color,” he said.

One of his earliest memories is of the color blue. Sosa and his family immigrated to New York City from the Dominican Republic when he was 3 years old, flying Pan Am from Santo Domingo; Sosa loved the blue of the airline’s logo.

“Blue was the first color I attached an emotion or memory to. I remember the logo, the color of the carpeting, the taste of the food, the flight attendants’ uniforms. That color has always stayed with me.”

Growing up in the Fort Apache section of the Bronx in the 1970s, Sosa was fascinated — amid the “chaos and destruction” — by glimpses of color inside burned-out apartment buildings. “You could see the interior walls,” he said, “since half the building was gone.”

His father worked as a super and handyman; his mother worked at a plastics factory. He stuttered, couldn’t play baseball and had trouble fitting in.

“I never felt I belonged, I never felt I looked right, I never felt anything was right about me,” he said. “But then a teacher of mine used art to try to get me to come out of my shell. She put a colored pencil in my hand, and I never let it go.”

He designed his first piece of clothing when he was 15: a blouse for his mother. He can still picture the print — in gold, brown, emerald, mustard — acquired at a fabric store near Union Square he’d once been afraid to enter. (His aunt, a seamstress, sewed the garment; Sosa wouldn’t dare sew around his father.)

Initially, theater wasn’t on Sosa’s radar. That changed when, while studying fashion design at the Pratt Institute in Brooklyn, he took a summer job with Grace Costumes, founded by the stage costumer Grace Miceli. At the end of the day, he would volunteer to sweep up, sticking around to watch Miceli and her artisans at work.

“It gave me an appreciation for the craftspeople — the makers,” he said. “It was better than getting a graduate degree from some tony-ass school. It was, ‘We need this costume done by 12 o’clock.’”

After graduation, Sosa worked as an assistant wardrobe supervisor for the Alvin Ailey American Dance Theater and styled music videos for SpikeDDB, the advertising agency founded by the director Spike Lee. Designing commercials, some only 15 seconds long, Sosa learned the importance of making an immediate visual impact. “Spike told me, ‘The audience needs to know who this person is the moment they step in front of the camera.’”

But Sosa felt drawn to Broadway most of all, intrigued by the way a single costume could speak volumes.

“He’s an innate storyteller,” said Stevie Walker-Webb, the director of “Ain’t No Mo.’” “He uses textiles instead of words, silhouettes instead of sentences.”

A memorable moment in “Ain’t No Mo’” involved a character named Black — an incarnation of Blackness that bursts onto the stage wearing a quilt. The idea for the costume emerged from a Zoom call with Walker-Webb. Sosa noticed something behind the director; it was a photo of a 150-year-old family quilt, stitched by the director’s great-, great-, great-grandmother and passed through many generations. With that image as the seed, the character became, according to Walker-Webb, “a living, breathing pastiche of Black history and culture.”

“It’s that sensitivity, and curiosity, that makes Emilio an invaluable collaborator,” he said.

There’s anothers project Sosa takes very seriously: improving diversity backstage. In 2021, he was elected chairman of the American Theater Wing, a nonprofit that offers professional development opportunities to emerging theater artists. He closely observes the Springboard to Design program, which encourages and mentors students from communities underrepresented in the theater design industry. “They meet fellow costume designers who look like them,” he said. “We need more set designers of color, more lighting designers of color. I’m always trying to push young kids to get into those departments.”

As busy as Sosa has been, this was also a year of learning for him. “I had to really dig deep, and really focus, and step my game up just to survive my schedule,” he said. If an intense schedule is the new norm, he’s prepared to make it work.

“Planes, trains, and automobiles. Buses, park benches. I could sketch in the middle of Times Square if I had to.”