Another essential quality of Jedi masters is that they are looked upon as leaders by others. Odin fits that description in multiple ways, whether to the people of Asgard as its former King and protector of the Nine Realms or to his children, Thor and Loki.
In his later years, Odin was regarded with tremendous wisdom and honor, making the appropriate decisions to protect Asgard. At times, that required doing grave things such as banishing his daughter Hela or stripping Thor of his powers in a significant teaching lesson. Those are the tough decisions that only a Jedi master is often willing to make.
That turnaround, though, took time for Odin. He used to be a passionate fighter but ultimately came to realize that peace was needed in a universe constantly imbued in war, and also, that his son was fit to lead Asgard into the light more so than himself.
Like the Ancient One, Odin continued to live on in his sons after his death, in the type of everlasting spirit that Jedi often possess. Realization and decisions like the ones Odin made throughout the MCU, along with the realization of a life much bigger than himself, make him a worthy Jedi master.