MLB Prediction Market Promos Today, August 12: Kalshi, Polymarket Offers for Mariners-Yankees

If you’ve never traded a contract before, tonight is a good night to start, as MLB prediction market promos only take about four minutes to claim. Tonight’s schedule runs deep, but the game I keep coming back to sits in the Bronx: Bryce Miller and the Mariners against Will Warren and the Yankees (7:05 p.m. ET on ESPN). Tonight marks the middle game of a three-game set, which is the kind of MLB matchup where the numbers on your screen move a lot between now and first pitch.

Prediction market apps let you buy and sell contracts tied to real outcomes. Prices sit between one cent and a dollar and move as money comes in, so you read a live market rather than a fixed number posted by a sportsbook. Polymarket, Kalshi, FanDuel Predicts, Novig, DraftKings Predictions and ProphetX all list Mariners vs. Yankees, and all six will pay you something just for showing up.

I’ve pulled the six best MLB prediction market promos into one table so you can size them up in a few seconds. Sign up now, fund your account, enter a position before Miller throws his first pitch.

Prediction Markets	MLB Prediction Market Promos	Sign-Up Link
Polymarket	Deposit $20, Get $50 in Bonus Funds	LABS
FanDuel Predicts	Sign Up & Unlock Your Offer	Click Here
Kalshi	Trade $25, Get Up to $500 Bonus	LABS
Novig	Spend $25, Get $50 in Novig Coins	BCLABS
DraftKings Predictions	Trade $5, Get $150 in Predictions Dollars	Click Here
ProphetX	Trade $10, Get $20 Bonus	LABSMAX

Best MLB Prediction Market Promos on Aug.12

Below is the detail on all six platforms, including the code you need, what you have to do to unlock the bonus, and which states each one serves. A couple pay on your deposit, a couple pay on your first trade, and the ceilings range from $20 to $500.

1. Polymarket

Polymarket handles more volume than anyone else in this space, and provide tight spreads, plenty of size, and competitive odds on a game like Mariners-Yankees. That matters if you want to trade around the game rather than just sit on a position.

Enter Polymarket promo code LABS during sign-up, drop in $10, and Polymarket hands you a $20 trading bonus on top of it. Triple your starting stack before clicking on a single market. The interface is user-friendly and easy to navigate in my experience, so finding Mariners-Yankees MLB lineups to trade is pretty straightforward.

Polymarket Promo Code	Polymarket Referral Bonus	Polymarket States Available
Polymarket Promo Code LABS	Deposit $20, Get $50 in Bonus Funds	AL, AK, AR, CA, CO, CT, DE, FL, GA, HI, ID, IN, IA, KS, KY, LA, ME, MN, MS, MO, NE, NH, NM, NJ, NY, NC, ND, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY, DC

2. FanDuel Predicts

If you’ve had a FanDuel account before, FanDuel Predicts feels immediately familiar. This prediction market has the same design language, response time, and account experience, with the exception that their picks are pointed at event contracts instead of a bet slip.

The FanDuel Predicts promo code is the simplest amongst MLB prediction market promos on this page. Sign up for an account and collect your new user bonus. There’s no code to type in, which streamlines how fast it is to start trading.

FanDuel Predicts Promo Code	FanDuel Predicts Welcome Offer	FanDuel Predicts States Available
FanDuel Predicts Promo Code (Click Here)	Sign Up & Unlock Your Offer	AK, AL, CA, DE, FL, GA, HI, ID, MN, ND, NE, NM, OK, RI, SC, SD, TX, UT

3. Kalshi

Kalshi is a CFTC-regulated exchange, meaning federal oversight, real contract specs, and no ambiguity about what you own are their biggest strengths. Kalshi also runs the widest board of any prediction markets I saw during my time trading MLB markets Trade on the Mariners-Yankees game, take a position on Seattle’s postseason odds, and more.

Use Kalshi promo code LABS, trade $25, and be eligible for up to $500 in bonuses. That’s the biggest ceiling among these MLB prediction market promos by a wide margin. That said, you aren’t guaranteed $500, as there are five bonus tiers ranging between $15 and $500 that you receive.

Kalshi Promo Code	Kalshi Referral Bonus	Kalshi States Available
Kalshi Promo Code LABS	Trade $25, Get Up to $500 Bonus	AL, AK, AR, CA, CO, CT, DE, FL, GA, HI, ID, IN, IA, KS, KY, LA, ME, MN, MS, MO, NE, NH, NM, NJ, NY, NC, ND, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WV, WI, WY, DC

4. Novig

Novig stands out with their peer-to-peer structure in comparison to other MLB prediction market apps. In a game like Mariners vs. Yankees where the home team is the favorite, that structure potentially leaves you with a better price than what’s available on competitor sites.

Punch in Novig promo code BCLABS, spend $25, and pick up $50 in Novig Coins. Use Novig Coins as free-play currency inside the app. Novig Coins cannot be withdrawn as cash. Novig Cash is a separate currency able to be withdrawn for real money prizes.

Novig Promo Code	Novig Sign-Up Bonus	Novig States Available
Novig Promo Code BCLABS	Spend $25, Get $50 in Novig Coins	AK, AR, FL, GA, HI, IL, IN, IA, KS, KY, ME, MA, MN, MO, NE, NH, NC, ND, OH, OK, OR, SC, SD, TX, VT, VA, DC, WI, WY

5. DraftKings Predictions

When it comes to the best raw and guaranteed value, the DraftKings promo code is the cream of the crop. No code is required during registration, so submit a $5 trade to unlock $150 in Predictions Dollars. This 30-to-1 return on your qualifying activity is one of the brightest features I saw amongst all MLB prediction market promos.

The other reason to register with the DraftKings Predictions promo code is due to how widely available it is. DraftKings Predictions is live in 48 states, with the only exceptions being New Hampshire and Maine.

DraftKings Predictions Promo Code	DraftKings Predictions Welcome Offer	DraftKings Predictions States Available
DraftKings Predictions Promo Code (Click Here)	Trade $5, Get $150 in Predictions Dollars	AL, AK, AZ, AR, CA, CO, CT, DE, FL, GA, HI, ID, IL, IN, IA, KS, KY, LA, MD, MA, MI, MN, MS, MO, MT, NE, NV, NJ, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY

6. ProphetX

ProphetX closes out the list of MLB prediction market apps with the smallest ask of all. Type ProphetX promo code LABSMAX during registration, trade $10, take a $20 bonus. Double up your account balance at the price of a $10 trade.

Coverage is the other selling point, as ProphetX operates in 49 states (excluding Nevada). This makes ProphetX a reliable fallback when geography gets in the way of the other MLB prediction market promos on this page.

ProphetX Promo Code	ProphetX Welcome Offer	ProphetX States Available
ProphetX Promo Code LABSMAX	Trade $10, Get $20 Bonus	AL, AK, AZ, AR, CA, CO, CT, DE, FL, GA, HI, ID, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, MN, MS, MO, MT, NE, NH, NJ, NM, NY, NC, ND, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY