Short answer
Not as a festival. Most Hanafi scholars in Bangladesh and India say Muslims should not join Pohela Boishakh rituals such as the Mangal Shobhajatra procession with masks and animal figures, puja, or mixed music events. A family meal, new clothes or new account books opened with a dua are not haram in themselves. Some scholars treat the day more lightly as national culture.
Treating a day as a yearly festival is not permitted when Islam has given its two Eids, and joining rituals with roots in other religions or with haram elements is haram. Eating, dressing well and doing business on that day as on any other day is permissible.
The four schools agree on this.
Explanation
Pohela Boishakh is the first day of the Bengali year, in mid April, celebrated in Bangladesh and West Bengal. The Bengali calendar is commonly traced to the Mughal era, when it was used for collecting land revenue at harvest. Today the day mixes several things: fairs, music, new clothes, special food, businesses opening new account books (halkhata), and in Hindu homes, puja. In Dhaka a large procession, long known as the Mangal Shobhajatra, carries masks and big figures of animals and birds.
Most Hanafi muftis advise Muslims not to celebrate it as a festival, for three reasons. The Prophet ﷺ replaced the Madinans' old festival days with the two Eids. Several of its customs come from other religions or carry beliefs about luck and evil. And many events involve music and free mixing that Islam does not allow.
- Avoid: puja and religious rites, the processions with masks and animal figures, and mixed concerts.
- Fine as on any day: a family meal, wearing clean new clothes, a day off, or a shopkeeper opening new books with bismillah and a dua for barakah.
- Greetings: the cautious view avoids festival greetings and prefers a general kind word, such as wishing someone a good year.
Some scholars and many Bangladeshi Muslims see the day as national culture with no religious meaning, and allow joining clean cultural events. This is a real difference, so keep it calm with family and friends. See is celebrating New Year's haram and Lunar New Year.
The evidence
Quran, Surah Al-Furqaan 25:72
وَٱلَّذِينَ لَا يَشْهَدُونَ ٱلزُّورَ وَإِذَا مَرُّوا۟ بِٱللَّغْوِ مَرُّوا۟ كِرَامًۭا ﴿٧٢﴾
And [they are] those who do not testify to falsehood, and when they pass near ill speech, they pass by with dignity.
Early scholars explained this as not attending the festivals of other faiths.
Sunan Abi Dawud 1134
Graded sahih... قد أبدلكم الله بهما خيرا منهما يوم الأضحى ويوم الفطر ...
"Allah has given you something better than them: the day of al-Adha and the day of al-Fitr."
Islam replaced the old festival days with the two Eids.
Sunan Abi Dawud 4031
Graded hasan sahih... من تشبه بقوم فهو منهم ...
"Whoever imitates a people is one of them."
Muslims avoid adopting the religious customs of other faiths.
Where the ruling is recorded
- al-Fatawa al-Hindiyya, Kitab al-Siyar, the chapter on the rulings of apostates. Warns against honouring the festival days of other religions, such as Nayruz.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.