Whoop has inked the second-largest office lease in Boston this year at Related Beal’s Kenmore project.

The wearable health technology maker plans to move its headquarters after signing a 121K SF lease at One Kenmore Square next spring, Related Beal announced Thursday.

Whoop will lease all eight office floors and a first-floor retail space at the new Commonwealth Building, a significant expansion after it raised a $100M Series E funding round in October that valued the company at $1.2B. Investors in the company include star athletes like the NFL's Patrick Mahomes, the NBA's Kevin Durant and pro golfers Rory McIlroy and Justin Thomas. The company currently occupies 30K SF at Samuels & Associates’ nearby 1325 Boylston St.

“We intend to bring 1,000 jobs to our new global headquarters and look forward to calling Boston our home for years to come,” Whoop founder and CEO Will Ahmed said in a statement.

The 326K SF development includes the adjacent Beacon Building, which is being redeveloped into a seven-story, 198K SF lab and research building after the developer pivoted plans from offices last November.

Related Beal purchased the two buildings along with seven others from Boston University in 2016 for a combined $140M. The iconic Citgo sign sits atop the development, and Related Beal in 2018 reached a 30-year agreement with Citgo Petroleum Corp. to keep the sign in place.

Whoop’s lease is second this year only to Amazon’s 630K SF lease with WS Development for a future Seaport tower, set to host the e-commerce giant’s Alexa operations. Other large leases have been signed in the suburbs, but Whoop and Amazon are the lone 100K SF-plus deals in Boston’s city limits this year.

The Beacon Building hasn't yet secured a lease, but with Boston’s life sciences market characterized by low supply and high demand, it likely won't stay that way for long. Currently, 91 life sciences are seeking 3M SF in Greater Boston alone. Related Beal’s mid-construction pivot to life sciences is part of the Boston office market’s trend toward conversion to capture the scorching lab market.