She uses Make Up Forever Lift Concealer, which is super full coverage, and applies it with a blending brush. Then it's blended with a damp sponge, transclucent powder is applied on top with the same sponge, and then the excess powder is dusted off.
Her makeup artist also sometimes uses a lighter shade of loose powder to top the concealer, which makes the undereye area brighter when camera flashes go off.
To see where exactly she applies her concealer, check out this picture she posted:
You can see that she also uses the concealer as a reverse contour (using light colors to contour instead of dark colors) under her cheeks and around her mouth to make her cheekbones and lips pop out more.