“My God, my God, I can’t believe it,” said one of his friends, according to the video.

He was arrested by the intelligence ministry shortly after his song went viral in September, generating some 40 million views — close to 87 million people live in Iran — in 48 hours. He is currently out on bail and awaiting trial, and has made only one short video message since his release.

“I wrote this song in solidarity with the people who are critical of the situation like many of our artists who reacted,” said Hajipour in the video message, from early October.

In late September, protests erupted across Iran as tens of thousands of people, led by women and girls, demanded liberation from the Islamic Republic’s theocracy. The protests were set off by the death of Mahsa Amini, a 22-year-old who had been in the custody of the morality police on the allegation of violating hijab rules.

Iranians tweeted their reasons for protesting using the hashtag #baraye (or “#for”). Hajipour wove those tweets into lyrics, naming his song after the hashtag. He composed and recorded the song from his bedroom in his parents’ house in the coastal city of Babolsar.

As Iranians shared the reasons they were protesting via tweets, Hajipour wove some of them into his verses:

“For embarrassment due to being penniless; For yearning for an ordinary life; For the child laborer and his dreams; For this dictatorial economy; For this polluted air; For this forced paradise; For jailed intellectuals; For all the empty slogans”

For the past five months, everywhere Iranians congregated inside and outside the country, be it protests, funerals, celebrations, hikes, concerts, malls, cafes, university campuses, high schools or traffic jams, they blasted the song and sang the lyrics in unison:

“For the feeling of peace; For the sunrise after long dark nights; For the stress and insomnia pills; For man, motherland, prosperity; For the girl who wished she was born a boy; For woman, life, freedom…For Freedom.”

The Grammy will raise the song’s profile even more.

“‘Baraye’ winning a Grammy sends the message to Iranians that the world has heard them and is acknowledging their freedom struggle,” said Nahid Siamdoust, the author of “Soundtrack of the Revolution: The Politics of Music in Iran.” “It is awarding their protest anthem with the highest musical honor.”

Siamdoust, who is also an assistant professor of media and Middle East studies at the University of Texas at Austin, said that while music has played an important political role in Iran since the constitutional revolution a century ago, no song compared to “Baraye” in terms of reach and impact. “Music can travel and traverse homes and communities and spread sentiment in a way that few other means can achieve,” she said.

In a 2019 documentary short about his musical journey that recently aired on BBC Persian, Mr. Hajipour said that he began training as a classical violinist at the age of 8, started composing music at 12. He also said he has a college degree in economics but works as a professional musician, composing music for clients and recording his own songs.

He said that his passion was creating music that broke form and that he drew inspiration from the pain and suffering he experienced and witnessed.