In his first speech to parliament since winning the presidency, William Ruto, who cast himself as the champion of the poor in the August 9 poll, said he intended to establish a progressive income tax regime.
"We are overtaxing trade and undertaxing wealth," Ruto told parliamentarians on Thursday.
"I am committed and determined to ensure that our tax system is responsive to the needs of the economy," he added.
Ruto also promised to rein in borrowing to kickstart Kenya's economy, which is creaking under the weight of a $70-billion debt mountain.
East Africa's most dynamic economy is facing deep hardship with about a third of the country's population of around 50 million living in poverty.
Ruto, who was deputy to former President Uhuru Kenyatta, had a bitter falling-out with his boss while in office, lambasting his policies for increasing debt.
Ruto last month slashed the food and fuel subsidies introduced by Kenyatta.
British charity Oxfam said in a report earlier this year that the two richest Kenyans own more wealth than the bottom 30% of the population.