2 Chronicles 34:1

Josiah was made king when he was eight years old, and he reigned in Jerusalem thirty one years.

Jeremiah 1:2

when the LORD had first spoken with him, in the time of Josiah the son of Amon king of Judah, in the thirteenth year of his kingdom;

Zephaniah 1:1

This is the word of the LORD, which came unto Zephaniah the son of Cushi, the son of Gedaliah, the son of Amariah the son of Hezekiah: in the time of Josiah the son of Amon king of Judah.

1 Samuel 2:18

But the lad Samuel ministered before the LORD girded about with a linen ephod.

1 Samuel 2:26

But the child Samuel profited and grew, and was in favour both with the LORD and also with men.

1 Kings 3:7-9

And now LORD, my God, it is thou that hast made thy servant king instead of David my father. And I am a young lad and know not how to order myself.

1 Kings 13:2

and cried against the altar at the commandment of the LORD and said, "Altar, altar, thus sayeth the LORD: 'Behold, a child shall be born of the house of David, Josiah by name, which upon thee shall offer the priests of the hill altars that sacrifice upon thee, and shall burn men's bones upon thee.'"

2 Kings 22:1-20

Josiah was eight years old when he began to reign, and he reigned thirty one years in Jerusalem. His mother's name was Jedidah the daughter of Adaiah of Bozkath.

1 Chronicles 3:14-15

And Amon was his son, and Josiah was son to him.

2 Chronicles 24:1

Joash was seven years old when he began to reign, and he reigned forty years in Jerusalem. His mother's name was Zibiah of Beersheba.

2 Chronicles 26:1

Then all the people of Judah took Uzziah which was sixteen years old, and made him king in the room of his father Amaziah.

2 Chronicles 33:1

Manasseh was twelve years old when he was made king, and reigned fifty five years in Jerusalem.

2 Chronicles 33:25

And the people of the land slew all that had conspired against king Amon. And thereto the people of the land made Josiah his son king in his room.

Ecclesiastes 4:13

A poor child being wise, is better than an old king that doteth, and cannot beware in time to come.

Matthew 1:10-11

Hezekiah begat Manasseh; Manasseh begat Amon; Amon begat Josiah;

Treasury of Scripture Knowledge

Summary

Josiah was eight years old when he began to reign, and he reigned in Jerusalem one and thirty years.

Bible References

Eight years

2 Chronicles 24:1
Joash was seven years old when he began to reign, and he reigned forty years in Jerusalem. His mother's name was Zibiah of Beersheba.
2 Chronicles 26:1
Then all the people of Judah took Uzziah which was sixteen years old, and made him king in the room of his father Amaziah.
2 Chronicles 33:1
Manasseh was twelve years old when he was made king, and reigned fifty five years in Jerusalem.
1 Samuel 2:18
But the lad Samuel ministered before the LORD girded about with a linen ephod.
1 Kings 3:7
And now LORD, my God, it is thou that hast made thy servant king instead of David my father. And I am a young lad and know not how to order myself.
Ecclesiastes 4:13
A poor child being wise, is better than an old king that doteth, and cannot beware in time to come.