Activist investor Jeffrey Smith scored a win in his battle against Yahoo on Wednesday, gaining seats on an expanded board for himself and three allies.

In return, the founder of Starboard Value will back off of his proxy battle to unseat the internet portal’s entire board.

Smith has been pressing to persuade Chief Executive Marissa Mayer and the rest of the Yahoo board — who he believes have fiddled while the company’s assets have burned — to sell the company’s core assets.

Yahoo recently initiated an auction sale and received interest from as many as 10 bidders.

The addition of Smith and his allies to the Yahoo board appears to smooth the path for a sale to Verizon — one of the companies, sources said, placing a first-round bid.

“Jeff has a lot of money wrapped up in Yahoo,” one investor told The Post. “I don’t think he would have settled [for four board members] if it wasn’t going to go the way he wants it to go.”

Interestingly, back in January 2015, Smith had pressed for a merger between AOL and Yahoo to realize synergies. Verizon now owns AOL and is in a position to leapfrog both Google and Facebook in terms of overall digital ad inventory if a deal is consummated.

With the Smith deal, the Yahoo board will grow from nine to 11 — as two members, H. Lee Scott and Sue James, step down.

Robert Peck, an analyst with SunTrust, told investors in a note, “We think that if for some reason bids come in too low, the directors Starboard has added … should be helpful in strategy, other financial transactions, and streamlining the core.”

A more stable board, one not in danger of being totally replaced by shareholders, would help bidders feel more comfortable about negotiating an acquisition contract, the source added. “They won’t be thinking they’re going to be hassled by a new board. It’s a potential issue off the table.”

Yahoo is expected to whittle down the 10 first-round bids to around three this week, sources told The Post.