  In this paper, we describe invariant twisted K\"ahler-Einstein (tKE) metrics
on flag varieties. We also explore some applications of the ideas involved in
the proof of our main result to the existence of invariant twisted constant
scalar curvature K\"{a}hler metrics. Also, we provide a precise description for
the greatest Ricci lower bound of an arbitrary K\"{a}hler class on a flag
variety. By means of this description, we establish some inequalities related
to optimal volume upper bounds for K\"{a}hler metrics just using tools from Lie
theory. Further, we describe the set of tKE metrics for several examples,
including full flag varieties, the projectivization of the tangent bundle of
$\mathbb{P}^{n+1}$, and families of flag varieties with Picard number $2$.
