The traditional answer is Jeremiah
For centuries, readers have connected Lamentations with the prophet Jeremiah. The ancient Greek translation of the Old Testament introduces the book by linking its sorrow to Jeremiah after Jerusalem's fall. This fits what we know of him. Jeremiah had warned Judah that persistent rebellion would bring judgement, and he deeply mourned for his people when disaster came (Jeremiah 25:8-11; Jeremiah 9:1).
Jeremiah was in Jerusalem through its final desperate days. He saw the city under siege, the temple ruined, and many people carried away to Babylon. Lamentations speaks from within that kind of devastation, grieving over an emptied city and a people living with the consequences of sin (Lamentations 1:1-3; Lamentations 2:11).
Oh that my head were waters, and mine eyes a fountain of tears, that I might weep day and night for the slain of the daughter of my people!
Why the book does not give a name
Lamentations never says, "I, Jeremiah, wrote this." Unlike many prophetic books, it leaves its author unnamed. That means we should be honest: Scripture itself does not directly settle the question. Some modern scholars think another eyewitness, or more than one poet, may have shaped these laments.
Still, an unnamed book is not an unhelpful one. Its purpose is not to draw attention to the writer. It invites God's people to face grief truthfully, confess their sin without excuses, and bring their pain before the Lord (Lamentations 1:18; Lamentations 3:40-42).
A poet grieving a ruined city
Lamentations contains five carefully crafted poems. Several follow the order of the Hebrew alphabet, giving shape to sorrow that otherwise feels chaotic. The writer does not minimise the horror of Jerusalem's fall. Yet he also refuses to say that God has disappeared or that mercy is finished (Lamentations 3:19-23).
That balance sounds much like Jeremiah. He proclaimed God's holiness and warned of coming judgement, but he also held out hope that God would restore his people after exile (Jeremiah 29:10-14). Whether Jeremiah penned every line himself, Lamentations stands firmly in the spiritual world of his ministry.
It is of the Lord's mercies that we are not consumed, because his compassions fail not. They are new every morning: great is thy faithfulness.
What matters most for reading it
It is reasonable to say that Jeremiah is the traditional and most likely author, while recognising that the book does not name him. The larger message is clear. Jerusalem's suffering was not meaningless, and neither was the people's prayer. They could turn towards God even while the ruins still stood around them (Lamentations 3:31-33; Lamentations 5:19-21).
If you read Lamentations, don't rush past its sadness to get to hope. Let it show you that faithful prayer can include tears, questions, confession, and waiting. God made room for this book in Scripture because grief needs words too.