Short answer
Yes. MSG (E621) is the sodium salt of glutamic acid, made by fermenting plant starch or sugar with bacteria. It contains no animal or alcoholic ingredient, so it is halal. Worries about MSG and health are a medical question, not a religious one.
MSG is halal: plant, mineral and microbial ingredients are permitted by default. Halal certification is a reassurance, not a requirement.
The four schools agree on this.
Explanation
Glutamate is an amino acid found naturally in tomatoes, cheese, mushrooms, soy sauce and seaweed. It gives the savoury taste called umami. MSG is glutamate combined with sodium so it can be sprinkled like salt.
Today MSG is made by fermentation: bacteria feed on starch or sugar from corn, cassava, sugar cane or sugar beet and produce glutamic acid, which is purified and crystallised. No pork, animal fat or alcohol is involved. Two related flavour enhancers, disodium inosinate (E631) and disodium guanylate (E627), are usually made by fermentation too, but can sometimes come from fish or meat, so a certified product is the safer choice for those.
In Islam, food is halal by default unless there is a reason to forbid it. Allah tells people to eat what is lawful and good, and warns believers against forbidding good things He has made lawful. A seasoning made from plants and bacteria is clearly on the halal side. The four schools agree.
What to watch is the rest of the product, not the MSG. Instant noodles, crisps and stock cubes can contain MSG and also chicken or beef fat from non-zabiha animals, or pork. Check the whole label or use the halal food checker. For other additives see E-numbers.
The evidence
Quran, Surah Al-Baqara 2:168
يَٰٓأَيُّهَا ٱلنَّاسُ كُلُوا۟ مِمَّا فِى ٱلْأَرْضِ حَلَٰلًۭا طَيِّبًۭا وَلَا تَتَّبِعُوا۟ خُطُوَٰتِ ٱلشَّيْطَٰنِ ۚ إِنَّهُۥ لَكُمْ عَدُوٌّۭ مُّبِينٌ ﴿١٦٨﴾
O mankind, eat from whatever is on earth [that is] lawful and good and do not follow the footsteps of Satan. Indeed, he is to you a clear enemy.
Lawful, wholesome food is to be eaten.
Quran, Surah Al-Maaida 5:87
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تُحَرِّمُوا۟ طَيِّبَٰتِ مَآ أَحَلَّ ٱللَّهُ لَكُمْ وَلَا تَعْتَدُوٓا۟ ۚ إِنَّ ٱللَّهَ لَا يُحِبُّ ٱلْمُعْتَدِينَ ﴿٨٧﴾
O you who have believed, do not prohibit the good things which Allah has made lawful to you and do not transgress. Indeed, Allah does not like transgressors.
Good things should not be declared forbidden without evidence.
Where the ruling is recorded
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hazr wa al-Ibaha. Things are permitted by default unless evidence shows otherwise.
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.