Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Welcome Back (5 points): Complete the Saints Revival prologue.
Seppuku (40 points): Defeat the Ronin.
Brother's Keeper (40 points): Defeat the Brotherhood.
Remind Me of the Babe (40 points): Defeat the Sons of Samedi.
Crime Lord (50 points): Complete all levels of all activities.
Velvet Rope (15 points): Complete all levels of Crowd Control.
Demolition Man (15 points): Complete all levels of Demolition Derby.
Purple Haze (15 points): Complete all levels of Drug Trafficking.
Trickster (15 points): Complete all levels of Escort.
Do Not Talk About It (15 points): Complete all levels of Fight Club.
Reality Star (15 points): Complete all levels of FUZZ.
HeliGood (15 points): Complete all levels of Heli Assault.
Stuntman (15 points): Complete all levels of Trail Blazing.
Ambulance Chaser (15 points): Complete all levels of Insurance Fraud.
Wrecking Crew (15 points): Complete all levels of Mayhem.
Splatster Chief (15 points): Complete all levels of Septic Avenger.
...But It Sure Is Fun (15 points): Complete all levels of Snatch.
Blue Collar (10 points): Complete all levels of Tow Truck, Fire Truck, Ambulance, and Taxi diversions.
Duke of Stilwater (10 points): Find all stunt jumps in Stilwater.
Maverick Goose (10 points): Find all flying stunt locations in Stilwater.
Hi Fidelity (15 points): Find all CDs in Stilwater.
All-City (10 points): Find and spray all 50 tags in Stilwater.
Where's My Car? (10 points): Deliver all the cars to the chop shops.
Hello 47 (10 points): Kill all Hitman targets.
2 Quick 2 Pissed (15 points): Complete all races in Stilwater.
Romero's Hero (5 points): Complete the Zombie Uprising video game.
Surf's Up (5 points): Get 3 gold stars in Vehicle Surfing.
Duelist (25 points): Complete all Ronin missions in co-op.
Pot Luck (25 points): Complete all Samedi missions in co-op.
Separated at Birth (25 points): Complete all Brotherhood missions in co-op.
Partners in Crime (100 points): Complete all campaign missions in co-op.
Confidence Men (25 points): Complete all levels of all activities in co-op.
True Pal (10 points): Defeat your partner in a co-op diversion.
Strong Armed (10 points): Complete the Strong Arm tutorial.
Saint's Seven (30 points): Win all seven Ranked Strong Arm Activities, and win on all seven Strong Arm maps.
Spread the Love (30 points): Host and win an Xbox LIVE Party Game.
Tested (10 points): Win 10 Xbox LIVE Strong Arm matches.
Hoodlum (30 points): Earn 7 Multiplayer Badges.
Made (30 points): Earn 15 Multiplayer Badges.
Kingpin (40 points): Earn 30 Multiplayer Badges.

Additionally, there are ten secret achievements, all of which are currently unknown:

Secret achievement (80 points): Unknown.
Secret achievement (15 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (5 points): Unknown.
Secret achievement (10 points): Unknown.
Secret achievement (20 points): Unknown.