What determines who gets or becomes an MVP?

First off, the MVP will always be selected from the winning team. Then the MVP will be selected based on:

1. Person who completed the objective

   • Hostage rescued
   • Bomb planted (and detonated)
   • Bomb defused
   • Arms Race winner

2. If the round was won by a team getting eliminated

   1. Player with most kills on the winning team
   2. Number of assists, if two or more people have the same amount of kills
   3. If the score of kills + assists is still the same the player who joined the server first will be MVP (first out of the ones with equal scores, not out of all players)

3. No MVP

   • Round draw
   • rare, but possible: time runs out and no damage was done on the winning team

Source for most of this: CS Wiki

MVP is determined by who did the most toward playing the objective, then style, then kills, etc. For instance, blowing the bomb > 1 knife > 1 headshot > 2 kills. If a particular user is going above and beyond for the round, they get the MVP.

Objective (DEfusal or Counter-Strike hostage rescue) > Style of Kills > # of Kills. (Kills trumps style if kills >= half of team. Style trumps Objective if objective not completed. Objective trumps all if completed.)

Source is first-hand experience.

The MVP in my experience with competitive play is determined as follows:

• Must be a member of the team that won the round
• If the bomb detonated or was defused, whoever planted/defused.
• Whoever got the most kills. (4 kills guarantee MVP over defuse or plant)
• If players tied for most kills, whoever got their kills first.