Blake Shelton and Miranda Lambert
Country singers Blake Shelton and Miranda Lambert announced the end of their four-year marriage on 20 JulyREUTERS/Eric Henderson

They have only just announced their separation but the marriage between country power couple Blake Shelton and Miranda Lambert has officially come to an end.

TMZ reports that the former couple's divorce was granted by a judge in Oklahoma on the same day they publicly announced their separation.

According to the publication, Shelton, 39, filed for divorce two weeks prior to their split announcement with proceedings reportedly finalised on 20 July.

It is believed the divorce was granted so quickly as the singers had a prenuptial agreement in place prior to their marriage, making it easy to divide their assets.

The publication claims Shelton will keep their ranch in Oklahoma while Lambert, 31, will continue to reside in their Nashville family home.

Although the former spouses have not provided the reason for their split, the website alleges that Shelton discovered the Mama's Broken Heart singer had been unfaithful during their marriage.

Sources have reportedly told the publication that The Voice coach heard rumours that Lambert had cheated with a country singer and another who is not in the music industry.

They also allege that Shelton kicked the chart-topping singer out of their Oklahoma ranch upon discovering the reported infidelity and demanded she remove her animals off the farm.

In their statement, the couple explained that their separation was amicable, stating: "This is not the future we envisioned and it is with heavy hearts that we move forward separately.

"We are real people, with real lives, with real family, friends and colleagues. Therefore, we kindly ask for privacy and compassion concerning this very personal matter."

Shelton and Lambert married in 2011 after five years of dating.