Short answer
No. Jinn are a separate creation made from smokeless fire, with free will like humans: some are Muslim and righteous, others are disbelievers. The rebellious ones are called shayatin (devils), which is the closest idea to "demons". Every devil among the jinn is a jinn, but not every jinn is a devil.
Belief that jinn exist is required, since the Quran states it plainly. Jinn are accountable (mukallaf) like humans. Seeking help from jinn, consulting fortune tellers who claim to use them, or practising magic is haram, and some forms of it are kufr.
The four schools agree on this.
Explanation
The Quran says, "He created the jinn from a smokeless flame of fire" (55:15), before humans. The Prophet ﷺ said the angels were created from light, the jinn from smokeless fire, and Adam from what you have been told. They are hidden from us, eat, marry, have children and die.
Jinn choose, as we do. In Surah al-Jinn some of them say: "Among us are the righteous, and among us are others not so" (72:11), and "among us are Muslims, and among us are the unjust" (72:14). Iblis is a jinn, and the jinn who follow him in rebellion are the shayatin. So "demon" fits the evil jinn, not the whole species. See Are jinn evil?
Folklore has piled a lot onto the word. The "genie in a lamp" who grants three wishes comes from storytelling, not from the Quran. Jinn worked for Sulaiman only by Allah's permission (34:12), and they have no power to grant wishes or know the unseen. Western ideas of demons as fallen angels also do not fit Islam, where angels never disobey. See Is Shaytan an angel?
Trying to contact jinn, using them through magic, or visiting those who claim to is forbidden. The Prophet ﷺ said that whoever goes to a fortune teller and asks him about something, his prayer is not accepted for forty nights. Hanafi scholars differed about the reward of believing jinn: Imam Abu Hanifa is reported to have held that it is safety from the Fire, while his two students held they enter Paradise. Read more in Jinn in Islam.
The evidence
Quran, Surah Ar-Rahmaan 55:15
وَخَلَقَ ٱلْجَآنَّ مِن مَّارِجٍۢ مِّن نَّارٍۢ ﴿١٥﴾
And He created the jinn from a smokeless flame of fire.
Jinn are a distinct creation made from fire.
Quran, Surah Al-Jinn 72:11
وَأَنَّا مِنَّا ٱلصَّٰلِحُونَ وَمِنَّا دُونَ ذَٰلِكَ ۖ كُنَّا طَرَآئِقَ قِدَدًۭا ﴿١١﴾
And among us are the righteous, and among us are [others] not so; we were [of] divided ways.
Some jinn are good and some are not.
Quran, Surah Al-Jinn 72:14
وَأَنَّا مِنَّا ٱلْمُسْلِمُونَ وَمِنَّا ٱلْقَٰسِطُونَ ۖ فَمَنْ أَسْلَمَ فَأُو۟لَٰٓئِكَ تَحَرَّوْا۟ رَشَدًۭا ﴿١٤﴾
And among us are Muslims [in submission to Allah], and among us are the unjust. And whoever has become Muslim - those have sought out the right course.
There are Muslim jinn.
Sahih Muslim 2996
Sahih... خلقت الملائكة من نور وخلق الجان من مارج من نار ...
"The angels were created from light and the jinn from a smokeless flame of fire."
Jinn and angels are different creations.
Sahih Muslim 2230
Sahih... من أتى عرافا فسأله عن شىء لم تقبل له صلاة أربعين ليلة ...
"Whoever goes to a fortune teller and asks him about something, his prayer is not accepted for forty nights."
Forbids seeking knowledge from those who claim to use jinn.
Where the ruling is recorded
- Akam al-Marjan fi Ahkam al-Jann (al-Shibli al-Hanafi), Chapters on jinn being accountable and on their reward. A Hanafi work that sets out the views on jinn, including Abu Hanifa's and his students'.
- Radd al-Muhtar (Ibn Abidin), Bab al-Murtadd, discussion of magic. Discusses when magic is kufr and when it is a major sin.
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.