For about eight years, Ivette Agosto arrived each morning before dawn at the Park Avenue headquarters of J.P. Morgan Chase & Co. and entered the skyscraper through the loading dock. She spent more than two hours preparing for the arrival of hundreds of bankers, knowing she played a crucial role in the firm’s operations: Ms. Agosto was J.P. Morgan’s star barista.

Ms. Agosto, 36 years old, knew who wanted coffee black, and who wanted a pumpkin loaf or a triple-tall mocha (a drink not even on the menu) at the Starbucks in the J.P. Morgan lobby. She memorized the names of regulars, many who dubbed her Happy Ivy due to her habit of greeting familiar faces with “Happy Friday!” at the end of the week.

Ms. Agosto’s popularity got noticed, and now she is steering customers toward debit cards instead of decaf.

Since November, Ms. Agosto has been working as a personal banker at the Chase retail branch about 50 yards from the ground-floor Starbucks within the bank’s headquarters. In her new workplace, which she enters through the front door, Ms. Agosto pitches products to customers, helps them get new debit cards and figures out why they were charged certain fees.

“I was pinching myself,” she said recently, although she noted that some of her friends in the Dominican Republic, where she grew up, didn’t fully understand her new role. She says she told them, “Chase, the bank. I’m not chasing people!”