Note: There are about 24 missions that can reward your Thieving Experience in OSRS. We have decided to mention something more interesting and valuable.
The Giant Dwarf (Optional, Skill Requirements: 14 Thieving, 16 Firemaking, 33 Magic, 12 Crafting, and optionally 20 Smithing, 20 Mining. 2500 Mining, Crafting, and Smithing Experience, 1500 Firemaking, Thieving, and Magic Experience). This is more like a mining / smith quest, but it's easy (and it's likely that the quest has already been completed when upgrading other skills).
Hazeel Cult (Optional/Recommended, Skill Requirements: None. Reward: 1500 Thieving Experience, 2000 Gold Coins). Very short, suitable for beginner tasks, you can quickly complete some preliminary thieves experience.
Tribal Totem (Optional/Recommended, Skill Requirements: 21 Thieving. Reward: 1775 Thieving Experience, 5 Swordfish). Another short and easy task, with low requirements, can complete some additional early rogue experience.
Death to the Dorgeshuun (Recommended, Skill Requirements: 23 Thieving, 23 Agility. Reward: 2000 Thieving Experience, 2000 Ranged Experience, access to the H.A.M Storerooms, access to Dorgesh-Kaan). There are some treasure chests in the H.A.M storage room. The guards patrolling in the pickpocket area can request keys. This means that this task provides another way to gain a good thief experience and a large number of cheap RuneScape gold.
The Queen of Thieves (Optional, Skill Requirements: 20 Thieving. Reward: 2000 Thieving Experience, 2000 Gold Coins, Access to The Warrens, 10% Piscarilius favor, an item that teleports you to the Port Piscarilius). Quest with close to zero requirements, and a short one to boot. Definitely worth doing if you are looking for something to do during breaks from Thieving Experience grinding.
Fight Arena (Recommended, Skill Requirements: None, Weapons, Food and Armor are required though. Reward: 12175 Attack Experience, 2175 Thieving Experience, the Khazard Armour). Proper use of safety points can make the boss in the mission savvy, which makes the mission an ideal place to start the journey of thieves (and attack skills).
The Slug Menace (Optional, Skill Requirements: 30 Runecrafting, 30 Thieving, 30 Slayer, 30 Crafting. Reward: 3500 Thieving Experience, 3500 Crafting Experience, 3500 Runecrafting Experience). This task is worth completing, especially if you also want to upgrade your rune skills.
Icthlarin's Little Helper (Optional/Recommended, Skill Requirements: None, but you will have to defeat Level 91 monsters during the Quest. Reward: 4500 Thieving Experience, 4000 Woodcutting Experience, 4000 Agility Experience, Catspeak Amulet, access to the Sophanem city). A very simple task with good experience rewards is also a prerequisite for some other valuable tasks.
Darkness of Hallowvale (Optional, Skill Requirements: 22 Thieving, 40 Strenght, 5 Construction, 33 Magic, 26 Agility, 32 Crafting, 20 Mining. Reward: 6000 Thieving Experience, 7000 Agility Experience, 2000 Construction Experience, a Tome of Experience). The tome of experience gained from this task can be used to assign a total of 6000 points of experience to the skills you choose (you can assign skills below 30 points to the three software packages of 2000 exp, and you can select the same skills multiple times).
Contact! (Optional, Skill Requirements: None. Reward: 7000 Thieving Experience, 7000 Experience to two other Skills of your choosing - Attack, Magic, Defense, Strenght, Hitpoints, or Ranged, The Keris, access to the Sophanem's Bank). Don’t because Fooled by lack of skill requirements, this is a master difficulty task only for the most experienced players, but the rewards are high.
Dragon Slayer II (Optional, Skill Requirements: 68 Mining, 75 Magic, 62 Crafting, 70 Smithing, 60 Agility, 50 Construction, 50 Hitpoints, 60 Thieving. Reward: 18000 Mining Experience, 25000 Smithing Experience, 15000 Agility Experience, 15000 Thieving Experience, access to the Myths' Guild, various other rewards). The task is very long and arduous, and it is only suitable for the most experienced and dedicated players, with appropriate high rewards.
The Feud (Recommended/Mandatory, Skill Requirements: 30 Thieving. Reward: 15000 Thieving Experience, the Desert Disguise, access to the Rogue Trader minigame, a Glass of Beer, ability to steal from Villagers, Bandits and Manaphite Thugs). This is a great Quest to do as soon as you reach Level 30 Thieving. Doing it at an appropriate level will rise your Thieving Level to 37. If you plan to speed up the thieves level, you must complete this task, because this is the fastest way to upgrade from level 30 to level 37 thieves. You still need to unlock blackjack, which is a very fast theft technique.
Mourning's Ends Part I (Optional, Skill Requirements: 50 Thieving, 60 Ranged. Reward: 25000 Thieving Experience, 25000 Hitpoints Experience, access to the Mourner HQ basement, access to the Village of Lletya, Mourner Clothing Set, Elf Teleport Crystal, the Fixed Device). Very long master difficulty task, get a high reward for thieves experience. If you meet all the requirements, it will be very interesting and worth completing, and the rewards are very interesting (Toad Cannon, yes).