Yemeni government forces launched attacks on the Houthis from three fronts in the north, west, and south of Yemen, according to military sources.
Additionally, Yemen's armed forces said they have begun a "strategic offensive" in Yemen's capital Sanaa.
The Iran-aligned Houthis have held the capital and vast parts of the northwest, where most of the population lives.
The Saudi-led coalition said that it is providing air cover for Yemeni armed forces on the ground, with 100 fighter jets reported to have taken part in the operation.
The coalition says it attacked 324 "high-value targets" and is providing air support at the Bab el-Mandeb Strait in the Red Sea.
This is a developing story.