RIYADH—Businesses looking for cash from Saudi Arabia’s $300 billion sovereign-wealth fund, one of the world’s most influential investors, have found it helps to enlist a former reality-TV producer from Sarasota, Fla.

Carla DiBello, 35, has become a high-profile figure in Saudi Arabia’s investment scene for her connections with the kingdom’s Public Investment Fund, or PIF. She is helping PIF negotiate a $445 million deal to buy a majority stake in England’s Newcastle United soccer team, say people familiar with her dealings. She has told acquaintances she was involved in talks around a $15 billion deal with Indian conglomerate Reliance Industries Ltd., say people familiar with the discussions.

Ms. DiBello also has a close relationship with the Saudi fund’s 49-year-old chief, Yasir al-Rumayyan. Their relationship has raised concerns among some PIF officials, who have grown frustrated with his attention to Ms. DiBello during a time when the fund’s major investments are struggling, Saudi officials at the fund say.

She has been helping foreign companies gain access to top Saudi officials, sometimes via formal business meetings and sometimes in more casual settings, say the people familiar with her dealings. Ms. DiBello arranges compensation for her role in such deals, generally from the company seeking PIF investment or from others involved in a potential transaction, often through her firm, Sarasota-based CDB Advisory, the people say.

Last year in New York City, Ms. DiBello helped a Juul Labs Inc. executive get a rare one-on-one meeting with Mr. Rumayyan, says one of the people. An investment in Juul didn’t happen, the person says, but the meeting was a coup for the Juul executive.