- This is the sort of advice and counsel you might find yourself delivering one day to a future President or Secretary of Defense. When you do, make sure it your best, most independent military opinion—neither constrained nor contaminated by personal politics. Part of the deal we made when we joined up was to willingly subordinate our individual interests to the greater good of protecting national interests. The military as an institution must remain a neutral instrument of the state, no matter which party holds sway. We give our best advice beforehand. If it's followed, great. If it's not, we have only two choices. Obey the orders we have been given, carrying them out with the professionalism and loyalty they deserve or vote with our feet. That's it. We don't get to debate those orders after the fact. We don't get to say, "Well, it's not how I would have done it," or "If only they had listened to ME." Too late at that point … and too cowardly. Few things are more damaging to our democracy than a military officer who doesn't have the moral courage to stand up for what's right or the moral fiber to step aside when circumstances dictate.
- There is, I am convinced, a sea of goodwill out in the country of people and places yearning to help. We need to tap into it. We need to make that connection. We need to come up with new ways and new ideas to make life better for those affected by this war, so that kids can go to school, incomes can be sustained, and homes can be both purchased and lived in for a long time. The truth is, we live in deeds, not days; in actions and thoughts and feelings, not heartbeats. If the untimely battlefield deaths of generations of American heroes have taught us nothing else, it should be this unalterable fact: what you do with your time here on earth is far more important than the time you had to do it. Those who live most are those who love most, who act the noblest and do their best.
- From Op-Ed "Memorial Day" (26 May 2008)
- Let us all be men and women in full. Let us expect from ourselves more than we think we can give, more than we think we can do and more than we think we already know.
- To Army War College Graduates, Carlisle Barracks, Pennsylvania, 7 June 2008
- We cannot kill our way to victory.
- On NATO in Afghanistan, Washington, D.C., 11 September 2008 
- If you listen closely to the voices of our veterans, you understand that yes, they all returned from war changed, but what never changed is this: They never forgot your generosity. They never forgot the power of opportunity. They never forgot the American dream. They want a job; they want their kids to go to school; they’d like an education, a career, a home. They want to make a difference. It is vital for communities throughout the land to be able to join up – in concert with DOD, VA – so that this dream is still possible for them – for those that sacrificed so much. But it goes far beyond what government can do. We must share the burdens of this war – now the longest conflict this nation has faced with an all-volunteer force since the American Revolution. I am convinced that America’s great sea of goodwill can be, in fact, a rising tide … a tide that could lift every veteran and every family of our wounded and fallen.
- To Soldiers' Angels Gala, Washington, D.C., 6 November 2008
- It is a really important place to not go, if we can not go there in any way, shape or form.
- On attacking Iran, Washington, D.C., July 2009.
- Mr. Chairman, speaking for myself and myself only, it is my personal belief that allowing gays and lesbians to serve openly would be the right thing to do. No matter how I look at this issue, I cannot escape being troubled by the fact that we have in place a policy that forces young men and women to lie about who they are in order to defend their fellow citizens.
- Congressional testimony on repealing DADT, 2 February 2010
Quotes about Mullen
- Along with his congeniality, [he] displayed fine leadership qualities. With his well rounded personality, his enthusiasm, and his desire to do his best, Navy-Air is indeed getting an outstanding officer.