The Sovereign Lord, The One with the complete Dominion, the One Whose Dominion is clear from imperfection
Allah is Al-Malik (in arabic: ٱلْمَلِكُ), the literal meaning in Arabic is "The King." He is the one who reigns dominion over the heavens and the earth and everything that resides within them. There is nothing above Him, and He is alone.
From the root mim-lam-kaf (م ل ك) which has the following classical Arabic connotations: to possess, to own exclusively to exercise authority to command to have power over, command, reign to have dominion over, to have ruling power to have kingship.
There is a difference in ٱلْمَـٰلِكُ (al-Malik) and ٱلْمَـالِكُ (al-Mālik), the difference is the second is pronounced with an added stress on the letter "a". Al-Malik is a king, a ruler over his subject whereas al-Mālik is the master and owner. Al-Malik is the king, whose limits are not confined to a boundary, He is ever-lasting in time and space. He can never be abdicated from His throne and doesn't need the support of His subjects. Our perception of a king is that he leads the people, but he requires buy-in from his subjects. Without the support of the people, he has no power, no dominion.Abu Dharr reported Allah's messenger ﷺ as stating that God most high says, "if the first and last of you, the living and the dead among you, those of you who are fresh and those of you who are withered, had all hearts as wretched as the heart of the most wretched of my servants, that would not diminish as much as a gnat’s wing from my dominion." 
This emphasizes how He has no need of any existing thing, he is independent. If all people were wretched in their hearts, i.e., they did not believe, he would still be the king. His dominion would not diminish even by a "gnat's wing."
Fata’aalal laahul Malikul Haqq; wa laa ta’jal bil Quraani min qabli ai yuqdaaa ilaika wahyuhoo wa qur Rabbi zidnee ‘ilmaa
"So high [above all] is Allah, the Sovereign, the Truth. And, [O Muhammad], do not hasten with [recitation of] the Qur’an before its revelation is completed to you, and say, "My Lord, increase me in knowledge." — (Qur'an 20:114)
Qulil laahumma Maalikal Mulki tu’til mulka man tashaaa’u wa tanzi’ul mulka mimman tashhaaa’u wa tu’izzu man tashaaa’u wa tuzillu man tashaaa’u biyadikal khairu innaka ‘alaa kulli shai’in Qadeer
"Say (O Muhammad SAW): “O Allah! Possessor of the kingdom, You give the kingdom to whom You will, and You take the kingdom from whom You will, and You endue with honour whom You will, and You humiliate whom You will. In Your Hand is the good. Verily, You are Able to do all things." — (Qur'an 3:26)
Fata’aalal laahul Malikul Haqq; laaa ilaaha illaa Huwa Rabbul ‘Arshil Kareem
"So exalted is Allah, the Sovereign, the Truth; there is no deity except Him, Lord of the Noble Throne." — (Qur'an 23:116)
Huwal-laahul-lazee laaa Ilaaha illaa Huwal-Malikul Quddoosus-Salaamul Muminul Muhaiminul-‘aAzeezul Jabbaarul-Mutakabbir; Subhaanal laahi ‘Ammaa yushrikoon
"He is Allah, other than whom there is no deity, the Sovereign, the Pure, the Perfection, the Bestower of Faith, the Overseer, the Exalted in Might, the Compeller, the Superior. Exalted is Allah above whatever they associate with Him." — (Qur'an 59:23)
From the hadith it mentions Allah’s Messenger (ﷺ) a saying, “The most awful name in Allah’s sight on the Day of Resurrection, will be (that of) a man calling himself Malik Al-Amlak (the king of kings).  There can be no king of kings, as Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is the king of kings. To say otherwise would be blasphemous.
Our belief that Allah is Al-Malik (The King) is beneficial for us. We seek refuge in Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ because only He can help us. We seek the bounty from the King of kings because He is the only provider with no limits.
This belief frees us from the shackles of dependence on wealthy leaders that may cause us to compromise our morals and integrity so that we may be in their favor. People will continually try to use fame, money, and power to control and influence our behavior for their benefit. But for the person who knows Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is al-Malik this breaks any hold they may have over us.
A person who has Allah only needs Allah, they are free from worldly desires. It enables them to fulfill their duties and obligations so that they may live like a King in the akhirah.