The Belgium international has impressed his former Sunderland team-mate in first-team training after completing a £9m move to the Reds from the Black Cats last month.
Mignolet faces stiff competition for the Liverpool number one shirt from long-term Reds first-choice goalkeeper Pepe Reina, who moved to Anfield in 2005.
And Henderson expects a very competitive battle between Mignolet and Reina to earn a starting spot next season as Brendan Rodgers’ men look to break into the top four.
“If you’ve seen training, and the game the other day, you saw he’s a very good goalkeeper,” Henderson told Liverpool’s website.
“He’s a very good shot stopper and, to be fair, he can do anything.
“He’s very good with the ball at his feet, has got good kicking and distribution, and his shot-stopping is unbelievable.
“It’ll definitely be interesting. Pepe [Reina] is an amazing ‘keeper, everyone knows that, so it’ll be good competition for them both.”