Heat the olive oil in a large pot over medium heat. Add the diced onion and minced garlic and cook for 4 to 5 minutes until the onion softens and the garlic becomes fragrant.
Add the broccoli florets and vegetable broth to the pot. Bring the mixture to a boil, then reduce the heat and simmer for 10 minutes until the broccoli is tender.
Stir in the drained white beans, salt, and black pepper. Continue to simmer for another 5 minutes so the beans warm through.
Remove the pot from the heat. Use an immersion blender to partially puree the soup, leaving some chunks of broccoli and beans for texture.
Stir in the lemon juice. Ladle the soup into bowls and top each serving with the chopped fresh parsley.