Mayor Andy Preston said each and every ward in the town would have its own - meaning at least 21 would soon be popping up.
A "micro forest" can be as small as a tennis court and includes lots of densely planted trees - around 600 in 250 square meters and with around 30 different species.
They are planted using a method invented by a Japanese botanist and are also known as Miyawaki Forests.
The trees grow more quickly and absorb more CO2 than plantations grown for timber.
Advocates for the method say the miniature forests grow 10 times faster and become 30 times denser and 100 times more biodiverse than those planted by conventional methods.
Scientists say such ecosystems are key to meeting climate goals, estimating that natural forests can store 40 times more carbon than single-species trees. The forests are designed to regenerate land in far less time than the 70-plus years it takes a forest to recover on its own.
Mr Preston said: "I'm really excited about this plan and I think people are really going to love these really intensely grown micro forests.
"When I was elected mayor I set a target of planting 10,000 trees in the town. It was never an easy ask but I felt it was really important.
"Earlier this year Middlesbrough was named a Tree City of the World and we're just continuing to build on that with new ideas like this one coming from elected representatives, council workers and members of the public.
"I think we're really onto something and we're going to soon see and feel the difference of a greener and more environmentally sustainable Middlesbrough."
The plan would commence in autumn 2021 and be completed by late spring 2022.
