Short answer
Animals will be brought back on the Day of Judgement so that justice is done between them, and then, according to the well-known explanation, they become dust. No authentic text says that pets enter Jannah. But in Jannah you will have whatever you wish for, so a believer who longs for a beloved pet will not be left grieving.
Animals are not held accountable like humans and do not enter Jannah or the Fire as reward or punishment. They are resurrected for justice between them and then turned to dust, as reported from Abu Hurayrah and others in explaining the Quran.
The four schools agree on this.
Explanation
The Quran says there is no creature on earth or bird with wings except that they are communities like you, and 'then to their Lord they will be gathered'. It also says that on that Day 'the wild beasts are gathered'. The Prophet ﷺ said that rights will be paid back on the Day of Judgement, even a hornless sheep will get justice from a horned sheep that butted it.
What happens after that? The Companion Abu Hurayrah explained that once justice is done between the animals, Allah tells them to become dust. That is when the disbeliever, seeing this, says 'I wish I were dust', as in Surah al-Naba. Animals do not carry the trust of obedience that humans carry, so they are not rewarded with Jannah or punished with the Fire.
Some books mention particular animals in Jannah, such as the dog of the People of the Cave or certain prophets' animals, but these reports are not authentic. Leave them aside.
For anyone grieving a pet, especially a child, there is real comfort:
- Allah says the people of Jannah will have whatever their souls desire. If you long for your cat there, Allah can give you that and more.
- The care you gave the animal is rewarded. The Prophet ﷺ said there is reward in serving every living being.
- Sadness at losing a pet is natural and not a weakness of faith.
See also Cats in Islam and Jannah in Islam.
The evidence
Quran, Surah Al-An'aam 6:38
وَمَا مِن دَآبَّةٍۢ فِى ٱلْأَرْضِ وَلَا طَٰٓئِرٍۢ يَطِيرُ بِجَنَاحَيْهِ إِلَّآ أُمَمٌ أَمْثَالُكُم ۚ مَّا فَرَّطْنَا فِى ٱلْكِتَٰبِ مِن شَىْءٍۢ ۚ ثُمَّ إِلَىٰ رَبِّهِمْ يُحْشَرُونَ ﴿٣٨﴾
And there is no creature on [or within] the earth or bird that flies with its wings except [that they are] communities like you. We have not neglected in the Register a thing. Then unto their Lord they will be gathered.
Animals will be gathered on the Day of Judgement.
Quran, Surah At-Takwir 81:5
وَإِذَا ٱلْوُحُوشُ حُشِرَتْ ﴿٥﴾
And when the wild beasts are gathered
Animals are brought back on that Day.
Quran, Surah An-Naba 78:40
إِنَّآ أَنذَرْنَٰكُمْ عَذَابًۭا قَرِيبًۭا يَوْمَ يَنظُرُ ٱلْمَرْءُ مَا قَدَّمَتْ يَدَاهُ وَيَقُولُ ٱلْكَافِرُ يَٰلَيْتَنِى كُنتُ تُرَٰبًۢا ﴿٤٠﴾
Indeed, We have warned you of a near punishment on the Day when a man will observe what his hands have put forth and the disbeliever will say, "Oh, I wish that I were dust!"
Explained by Abu Hurayrah as the disbeliever seeing animals turned to dust.
Quran, Surah Fussilat 41:31
نَحْنُ أَوْلِيَآؤُكُمْ فِى ٱلْحَيَوٰةِ ٱلدُّنْيَا وَفِى ٱلْءَاخِرَةِ ۖ وَلَكُمْ فِيهَا مَا تَشْتَهِىٓ أَنفُسُكُمْ وَلَكُمْ فِيهَا مَا تَدَّعُونَ ﴿٣١﴾
We [angels] were your allies in worldly life and [are so] in the Hereafter. And you will have therein whatever your souls desire, and you will have therein whatever you request [or wish]
The people of Jannah are given what they wish for.
Sahih Muslim 2582
Sahih... لتؤدن الحقوق إلى أهلها يوم القيامة حتى يقاد للشاة الجلحاء من الشاة القرناء ...
"Rights will be paid to their owners on the Day of Resurrection, even the hornless sheep will get justice from the horned sheep."
Animals are resurrected for justice between them.
Where the ruling is recorded
- Tafsir Ibn Kathir, Surah al-Naba, on ayah 40. Reports Abu Hurayrah's explanation that animals become dust after justice is done.
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.