The cash will used by the Super League club to purchase the site and its surrounding area, as it looks to redevelop its current ground to meet new standards.
Property group 88m bought Belle Vue in 2016 but are now expected to sell up.
It is hoped the cash will help stabilise the club and will reassure the Rugby Football League (RFL) there is clear intent on making the ground compliant with the new regulations.
At a recent planning meeting the council insisted it remained committed to the prospect of a community stadium, which was supposed to be at Newmarket Lane, and was supposed to be used by the club but is yet to be built by the land’s owners.
In a statement, Wakefield Trinity chairman John Minards said: "We are grateful for the support of Wakefield Council, without whom this purchase would not be possible.
"While it is great news that we will be owners of our own ground, this is only very much the first stage of our redevelopment plans and we continue to be in active discussions with a number of parties as we progress towards our ambitions for a world-class stadium fit for the 21st century."
Plans to increase Belle Vue's capacity to from 7,000 to a 10,000 seater ground were agreed in principle in 2017, but Trinity later threatened to take the council to court after branding the plan "uneconomical".
Now, the expansion looks set to go ahead.
The council's deputy leader Denise Jeffery said: "We have a proud history of rugby league in the Wakefield District and I’m pleased that this loan will help Wakefield Trinity secure the ownership of the stadium and provide a catalyst for development.
"We have been exploring the potential of redeveloping Belle Vue for some time and as I have said before, the council is committed to working with the club to support the development of a community stadium."
Hopes that the club may be relocated to Newmarket Lane in the long-term have been hit by repeated setbacks after the government gave a community stadium on the site planning permission in 2012.
Developers Yorkcourt are believed to be in talks with both the council and Wakefield Trinity but have yet to publicly say why the scheme has not made progress.