The 29-year-old was unable to come to an agreement with Atletico Madrid over a new contract and therefore left Diego Simeone's side on a free transfer at the end of June.
Hermoso's departure was a surprise considering that he was a vital player for Atletico during the 2023-24 campaign, making 45 appearances in all competitions.
The defender featured 174 times for the Red and Whites after arriving from Espanyol in 2019, and he also came up with 10 goals, demonstrating his ability to find the back of the net.
According to Spanish journalist Maximo de la Cruz Ramirez, Man United have opened talks with Hermoso and his representatives over a possible move to the 20-time English champions.
Hermoso 'emerges' as target for Man United
Ramirez claims that negotiations have only just started, but Hermoso has told the Red Devils that he would be looking for a three-year contract with a gross salary of around £5.1m per year.
Hermoso has spent the majority of his career as a centre-back, but he is also capable of operating at left-back, which remains a problem position for the 20-time English champions.
Tyrell Malacia missed the entirety of last season with a serious knee injury and is still not available, while Luke Shaw's ongoing muscular problems are concerning for the Red Devils.
Shaw is a major doubt for Saturday's Community Shield against Manchester City, with 17-year-old Harry Amass therefore in line to start at left-back for Erik ten Hag's side this weekend.
Hermoso could solve a big problem at Man United
Hermoso played 29 times in the Champions League during his time at Atletico, while his overall La Liga record for both Atletico and Espanyol is 10 goals and five assists in 185 appearances.
Players of Hermoso's age and ilk do not often become available on a free transfer, and it would certainly not be a surprise to see the defender make the move to Old Trafford.
With new signing Leny Yoro out until November, and a deal for Bayern Munich's Matthijs de Ligt seemingly no closer, Hermoso could be a smart acquisition for the Red Devils under the circumstances.
Harry Maguire is expected to stay at the club this summer, but Victor Lindelof is being linked with an exit, and Man United simply cannot afford to have more availability issues at the back during the 2024-25 campaign.