In 1551, a merchant market town called Jogasaki was established on the south bank of the Ōyodo River near Akae port, and flourished due to trade along the Seto Inland Sea with the Kinai region.

After the completion of the nationwide railroad system, many new people began to settle in the area.

[6] Miyazaki merged with the neighbouring town of Ōyodo and village of Ōmiya, and was raised to city status on April 1, 1924.

[7] On April 1, 1998, Miyazaki was designated a Core cities of Japan, giving it greater local autonomy.

[8] Miyazaki has a mayor-council form of government with a directly elected mayor and a unicameral city council of 40 members.

In terms of national politics, the city is part of the Miyazaki 1st district of the lower house of the Diet of Japan.

Rural parts of the city are still agricultural, cultivation of tomatoes, peppers, cucumbers, and other crops, and food processing factories.