The couple wed in an intimate ceremony in Los Angeles on Thursday, hours after Spears's ex-husband Jason Alexander attempted to crash the wedding site.
It took place at Spears's 12,464-square-foot Thousand Oaks, California home.
The Toxic singer, who arrived in a horse-drawn carriage, wore a custom Versace gown and wed in front of celebrity friends such as Donatella Versace, Paris Hilton and Drew Barrymore, according to reports.
Neither Spears nor Asghari have posted on social media about the nuptials.
Seven months ago, Spears was freed from a conservatorship that had prevented her from getting married.
Spears and Asghari have been together for five years. Asghari is a fitness professional, who has modelled in the past. He met Spears on the set of her Slumber Party video in 2016.
He was born in the Iranian capital Tehran, but moved to the US to be with his father when he was 12. Owing to the US immigration process, his family was not able to move together.
“It is with deepest sadness we have to announce that we have lost our miracle baby early in the pregnancy," the pair said in a joint statement posted to Instagram. "This is a devastating time for any parent.
“Perhaps we should have waited to announce until we were further along however we were overly excited to share the good news. Our love for each other is our strength. We will continue trying to expand our beautiful family.”
The wedding was not without controversy, after Alexander attempted to gain access to Spears's house.
Scroll through the gallery below to see inside Britney Spears's California home
Ventura County Sheriff’s Captain Cameron Henderson said officers responded to a trespassing call after 2pm on Thursday. He says Alexander was detained at the site of the ceremony and was arrested after officers noticed he had a warrant for his arrest in another county.
Alexander went on his Instagram live when he approached the event security. “She’s my first wife, my only wife,” said Alexander, who was briefly married to Spears — his childhood friend — in 2004. Their marriage lasted only 55 hours.
“I’m her first husband," he continued in the video. "I’m here to crash the wedding.”
Spears was previously married to Kevin Federline, with whom she has two sons, aged 15 and 16.