Mission accomplished
Definition 1 of 1
Pro Tip 1/3Success Declaration
Used to express that an objective or task has been achieved successfully and satisfactorily. 
She passed her driving test on the first try. Mission accomplished!
Pro Tip 2/3Colloquial Use
Common in casual conversation to indicate any completed activity, not just important tasks. 
I finally cleaned my room—mission accomplished!
Pro Tip 3/3Historical Reference
May remind people of specific events, like political statements, where it signaled a premature declaration of success. 
He finished his project, but much remains to fix—reminds me of 'mission accomplished' speeches.