The Prophet ﷺ explained this very directly. Anas ibn Mālik (may Allah be pleased with him) reported that the Prophet ﷺ said:
"Whoever forgets a prayer should perform it as soon as he remembers it; there is no expiation for it except that."
And he then recited the verse: {and establish prayer to remember me.} [Surat Tā-ha: 14]
[Sahih Bukhari 597, Sahih Muslim 684]
So the key point is: make it up immediately when you remember, and don't delay it further. The prayer is still valid and accepted, and you are excused for the oversight.
A few practical points to keep in mind:
1. Pray it exactly as you would normally pray Fajr — two rak'ahs (units), with the same conditions of purity, facing the Qibla, etc. There is no difference in how you perform it; you simply pray it late.
2. If you wake up after sunrise, you still pray Fajr as soon as you wake. The Prophet ﷺ also taught that whoever catches even one rak'ah of Fajr before sunrise has caught the Fajr prayer in its time [Sahih Bukhari & Muslim, hadith on catching one rak'ah]. But if the sun has already risen, you still make it up — you just don't delay it.
3. Don't confuse this with the two Sunnah rak'ahs of Fajr. The Prophet ﷺ was extremely consistent with the two voluntary rak'ahs before Fajr — ʿĀ'ishah (may Allah be pleased with her) said he was never more assiduous about any voluntary prayer than the two rak'ahs of Fajr [Sahih Bukhari 1169, Sahih Muslim 724]. If you missed those too, many scholars say it is good to make them up as well, but the obligatory Fajr is the priority.
4. Set a practical routine to avoid missing it. Use the prayer times feature in your Al Muslim Plus app to set a Fajr alarm, and place your phone or alarm clock away from your bed so you have to get up to turn it off.
A practical tip: If you do oversleep, don't fall into despair or self-blame — just get up, make wudu, and pray. The door of repentance and making up is open, and Allah is Most Merciful. Try to make it a habit to pray Fajr on time going forward, and ask Allah to help you wake for it.
If your situation involves a complex or recurring issue (for example, many years of missed prayers), it's best to consult a qualified scholar for a structured plan — but the general principle remains: pray each missed prayer as soon as you remember it.