Grand Finale is split into four different parts. For the first three parts the Protagonist has to chose a set of 2 Homies for each part. The Pairs are: Johnny Gat and Ben King, Pierce and Shaundi, Matt and Asha. Once the first three parts are completed, the Protagonist gets a special piece of power armour that gives them their superpowers and they fly through the ship and arrive at the throne room where they and Zinyak fight but the Protagonist eventually wins and becomes the leader of the Zin Empire.
The mission starts off with the Protagonist talking to Kinzie. She tells them to pick a pair who will go with them on the first part of the mission. This part of the mission involves defending the Key from Zin forces With an Alien RPG while the player's Homies drive the vehicle. The player is required to take out roadblocks and shoot tanks and UFOs that attack the vehicle. Once the player arrives at the Syndicate Tower they must defend CID while he opens the door then use telekinesis to move the key.
The second part of the mission requires the player to travel to three different portals with the next set of homies. At the first two portals you will have to defend the portals while Kinzie hacks into them. Once she is finished on each portal, things from those homies nightmares come through but are friendly. For the final portal you are all alone as you fight off Zin forces. Once the portal is ready you have to back away as Paul comes through and starts attacking the Zin. Soon the simulation starts to break down so the player must escape but some of the gateways are locked. Once the player gets through a gateway the simulation glitches out and brings the player to the Zin version of the Saints Row main menu. The player clicks continue and wakes up on the ship.
The third part of the mission takes part on Zinyak's ship as the player boards with his final set of two homies. The player fights through waves of Zin until they reach a locked door. One of your homies volunteers to hack into it so the player must defend them with their other homie against oncoming Murderbots and Zin. Once they are done the Protagonist orders them to get back to the ship while they go into the armoury and find power armour which gives them their powers back.
The final part involves the Protagonist flying through a large vent. The player has to avoid lasers and debris, destroy blast shield locks and reach the throne room. Zinyak and the Protagonist then fight. Zinyak gets a suit of power armour and creates a shield around him while the protagonist is attacked by explosive C.I.Ds and Zin troops. Once he destroys the shield generators your homies fly in and start to attack the Zin while you fight Zinyak. After a quick time event Zinyak is dead, his throne rises up and the Protagonist sits in it which shows he is the leader of the Zin. The Protagonist's steward, Zinjai tells him that they have discovered time travel so they could go back and save Earth.
- There are two endings to this mission, though it is not through anything the player does in the mission. If all loyalty quests are completed, then the player will unlock the true ending where the Saints discover time travel and the narrator will be revealed to be Jane Austen. If not all the loyalty quests are completed, then the player gets the non-canonical "bad ending" of the game in which the Saints do not discover time travel and the player will not get the "Saints and Sensibility" achievement
- The line at the beginning of the mission where the protagonist gives their speech to the crew members it ends with the line from "Reclamation" and "Three Kings", and "Return to Steelport" with the familiar "It's our time now. Let's get this shit started".
- At the start of the game, the ending scene is seen briefly, with the protagonist in "The Iron Saint" power armor.
- During the escape part, theis a fake crash with an message stating: "Error: DeadIsland_x_SaintsRow COMING 2015".
- It's a running joke because Keith David tell to the Protagonist that he play Dead Island for 12 hours when the Zin attack.
- Also, the last line of the fake crash is ERROR: PubFinder_TeeAichCue OUT OF MONEY (Error: Publisher Finder_THQ Out of Money).
- When the protagonist enters the room with "The Iron Saint" power armor and equips it, the sequence is a reference to how Isaac Clarke equips his armor in Dead Space.
- The song "The Touch" by Stan Bush plays when the protagonist gains the power armor and the conversation between the protagonist and Zinyak during the freefall segment, are both a direct reference to the 1986 Transformers movie between Megatron and Optimus Prime.
- The finale Quick time event battle does not require any buttons to be pressed.
- This quest is made up for 4 missions, which are visible in the quest log. After each mission, it is possible to quit and resume the current mission from the Quests menu. After completing side-quest missions, or saving and reloading, the current Grand Finale mission is auto-started.
- The phrase "You keep what you kill" has recently been popularised in the film The Chronicles Of Riddick.
- After completing the mission, the post-game tutorial text is titled "I came, I saw, I conquered", which is the English translation of Julius Caesar's famous line "Veni, vidi, vici".