A California developer has completed the $120 million acquisition of two parking lots in Boston’s Seaport Square, the final selloff of pre-approved development sites within the 23-acre master-planned district.

Pasadena-based Cottonwood Management LLC bought parcels M1 and M2 from Boston Global Investors (BGI) and Morgan Stanley, which acquired Seaport Square in 2006 and gained approvals for 6.3 million square feet of development.

Between Thursday’s deal and last week’s $359 million acquisition by WS Development, all of the land has now been sold off to the next generation of developers for apartments, office buildings, hotels and retail space.

The 3.5-acre property at Seaport Boulevard and East Service Road has permits in hand for an estimated $750 million development. Designed by Kohn Pedersen Fox Assoc., the project would include 750 condos and apartments and 125,000 square feet of retail space in three towers ranging up to 22 stories.

The buildings were designed with staggered setbacks, with 42-foot-tall podiums for the retail space and the residential towers rising behind them with stepbacks on higher floors for terraces. The visual effect is similar to that of books of varying sizes on a shelf, architects stated in submissions to city officials.

A 9,000-square-foot public square will be built in the center of the parcel, and two underground parking garages will contain 752 spaces.

The acquisition is the first in Greater Boston for Cottonwood, which was founded by MIT graduate Alexander Shing and manages residential properties on the East and West coasts.

“As we finalize our development plans for Parcels M1 and M2, our aim is to create a compelling mixed-use community and contribute to the city’s dynamic vision for the Seaport and Boston’s skyline,” Shing said in a statement.

Financing for the acquisition was provided by HGC Capital Group of Beijing and Celona Capital Group of Hong Kong.

BGI CEO John Hynes III said he originally had discussions with Celona about investing in his massive New Songdo City development in South Korea in the previous decade, and Celona also was interested in buying into Hynes’ attempted redevelopment of the former Filene’s site in Downtown Crossing. Celona’s interest in Boston real estate carried over to One Seaport Square, which ended up being acquired by Berkshire Group of Boston, and finally to the M1 and M2 parcels.

“They came back and said, `Look, we’re not done here yet. What else can we do?’” Hynes said. “We introduced them to the M block.”

Last week, BGI and Morgan Stanley sold 12.5 acres in Seaport Square that are pre-approved for 2.8 million square feet of development to Chestnut Hill-based WS Development for $359 million. Those parcels will include 1.25 million square feet of apartments and/or condos, 500,000 square feet of stores and restaurants, 400,000 square feet of office space and three hotels.

Skanska USA previously acquired two parcels for the 101 and 121 Seaport office towers, one of which is now occupied by PwC and the other which is being built on speculation. Watermark Seaport, a partnership between Skanska USA and Twining Properties, has begun leasing 346 apartments in its new 17-story tower on Seaport Boulevard. Other parcels will contain two parks, a micro-hotel, an office building and a relocated Our Lady of Good Voyage chapel owned by the Archdiocese of Boston.

Although Hynes’ company has sold off all of the development parcels in Seaport Square, BGI will continue to play an active role in the continuing build-out of the South Boston waterfront. The company remains the development manager for One Seaport Square and for all of the public realm improvements in the properties that WS Development bought last week.

“There’s a lot of heavy lifting coming along with that. We’ve still got a pretty good run of activity left in the Seaport,” Hynes said.

[This post was updated 10/30/2015.]