Online marketer HubSpot has signed a 100,000-square-foot lease expansion at the Davenport building at 25 First St. in East Cambridge.

The 12-year lease gives HubSpot occupancy of the entire 218,038-square-foot structured owned by Jamestown and updated by architects Sasaki Assoc. in 2008.

The Davenport was built in 1860 as the Davenport/Irving Casson Furniture Factory, and its seven buildings were renovated into an integrated office building in 1987.

Atlanta-based developer Jamestown acquired the property from DivcoWest in 2014 for $136 million. The building recently underwent $18 million in capital improvements, including a full lobby and common area renovation.

“This lease gives us the ability to keep building a pillar tech company in the Boston area while staying close to our roots,” J.D. Sherman, HubSpot president and COO, said in a statement.