According to the state-run Bahrain News Agency, the king appointed Lieutenant General Adel bin Khalifa Al Fadhel, as the new head of the National Security Agency [NSA].
Al Fadhel is taking over from Talal bin Mohammed bin Khalifa Al Khalifa, who lasted a little over a year in the post.
Meanwhile, in a separate decree the king also appointed Sheikh Talal bin Mohammed bin Khalifa Al Khalifa as new deputy interior minister.
Both the NSA and Manama's interior ministry have played a central role in crushing dissent in the Persian Gulf kingdom.
The reshuffle comes just weeks after three Bahraini human rights groups compiled a detailed report that documented the NSA's widespread abuses.
The Chambers of Death report was released by the Persian Gulf Institute for Democracy and Human Rights [GIDHR], the Bahrain Forum for Human Rights [BFHR] and Salam for Democracy and Human Rights on August 22 before being widely circulated by mainstream media outlets, including Reuters and The New York Times.
The tiny Persian Gulf kingdom, which is home to the US 5th Navy fleet, has witnessed a brutal crackdown by the Al Khalifa regime on its dissidents after it had put down a pro-democracy uprising in 2011.