Marketing and e-commerce company Tinuiti Inc. has agreed to acquire connected TV ad-buying shop Bliss Point Media Inc., the companies said, marking the New Mountain Capital-backed company’s second purchase in recent months.

Bliss Point, a seven-year-old Santa Monica-based company that specializes in buying digital-streaming and connected-TV ads, expects to generate about $50 million in revenue this year, a 200% increase from last year, said Tinuiti Chief Executive Officer Zach Morrison. After the deal closes, the combined companies will likely generate about $250 million in revenue this year, he said.

The companies declined to disclose the terms of the deal.

“We’ve got to stay ahead in culture, capabilities and technology,” said Mr. Morrison, who first met Bliss Point CEO Sean Odlum over video last summer. “We still believe consumer attention is massively focused on search, social and marketplaces or retail media, but the biggest place that consumer attention has gone is obviously OTT and connected television.”

OTT, an abbreviation for over-the-top, refers to TV that is distributed through an internet connection rather than through broadcast or cable.

Tinuiti, which is focused on e-commerce services, digital marketing and ad buying in search and social media, will integrate Bliss Point’s connected-TV capabilities and expand Bliss Point’s proprietary buying and planning technology across other categories, Mr. Morrison said.

The companies are merging as advertisers increasingly shift spending to connected TV and seek support in making sense of a fragmented digital media and marketing industry.

“As we and clients are getting bigger, the problems we are collectively trying to solve are getting more complex,” said Mr. Odlum. He said that adding digital expertise in areas like search, social and retail media will make it possible for the company to support marketers asking for help with ad placements across an increasing number of media channels.

Tinuiti, which in December announced an investment from New Mountain Capital that made the private-equity investor its majority owner, has plans to expand its business as it strives for a growing share of the digital marketing pie.

The company in March announced an agreement to acquire the Ortega Group LLC, a company that specializes in sales on Amazon, and that it was adding new board members including Kevin Mayer, briefly chief executive of TikTok.

It is also setting its sights on possible acquisitions in areas such as data, technology and creative capabilities, as well as firms that can help it expand its international presence, said Mr. Morrison.

“Yes, we are going to be more acquisitive,” he said. “We think about the industry and where the velocity of dollars are going.”

Write to Alexandra Bruell at alexandra.bruell@wsj.com