The 35-year-old has spent his entire career competing in his homeland, the German either representing Dortmund or Bayern Munich.
A total of five Bundesliga titles and three DFB-Pokals have been won since 2010-11, but the veteran will now take a different path.
Earlier this month, it was revealed that the centre-back would be departing the Westfalenstadion at the end of his contract, which expires on June 30.
At the time, Hummels declared that it had been "a huge honour" to spend 13 years of his career at Dortmund, acknowledging that he would continue to support them "from afar".
Hummels to make move to La Liga?
According to his representative Timo Boll, Hummels is closing in on completing a move to Spanish side Mallorca.
As quoted by Mallorca Zeitung, Boll said: "It's just a matter of details. Since neither [Hummels nor his father] speak Spanish, they called me.
"We were also involved in the ultimately failed transfer of John Brooks [in 2022]. [Hummels] doesn't care about money. He just wants to live in peace."
Furthermore, it has been noted that Hummels has a property on the island, adding to the likelihood that a transfer will soon be finalised.
How did Mallorca fare during 2023-24?
Mallorca have spent four of the past five campaigns competing in the top tier of Spanish football, their only time out of it being a promotion season in 2020-21.
In the last two campaigns, there has been excitement of some sort, with Mallorca earning their first top-half finish in La Liga for more than a decade in 2022-23.
Although they could only finish in 15th spot during the most recent campaign, Mallorca reached the final of the Copa del Rey, where they agonisingly lost to Athletic Bilbao on penalties.
Former Osasuna boss Jagoba Arrasate has just been appointed as their new head coach.