4-Bed Single Family Residence at MASHTA ISLAND in Key Biscayne

$18,500,000

Brickellsold Estimate* (fallback: list price)$18,500,000 (list price)

Listing courtesy of Coldwell Banker; Javier Gustavo Quiroz. Information from the Southeast Florida Multiple Listing Service is deemed reliable but is not guaranteed accurate.

For Sale
bedrooms

4

bathrooms

4

Square Footage

2255

Type of Property

Single Family Residence, Residential

Details

Overview

Sub Type
Single Family Residence
Price Per Sqft
$8,204/sqft
Built In
1958
Taxes
$112,485/yr

Description

BRING ALL OFFERS! Exceptional waterfront opportunity in prestigious Key Biscayne. Set on a 15,000 sq. ft. lot with 100 feet of water frontage, this residence offers open-water views, direct Biscayne Bay access, and no fixed bridges to the ocean. Currently undergoing a complete renovation, it will feature modern finishes, impact windows and doors, new systems, spacious living areas, a chef's kitchen, and luxurious bathrooms. Enjoy a private dock, deep-water access, pool, breathtaking sunsets, and an unmatched boating lifestyle in one of South Florida's most desirable communities One of the most compelling waterfront opportunities currently available in all of Key Biscayne. Perfectly positioned on the exclusive and highly coveted Mashta Island, this exceptional property offers approximately 100 feet of prime waterfront, deep-water dockage, direct Biscayne Bay access, and no fixed bridges to the Atlantic Ocean, creating an unparalleled opportunity for boating enthusiasts and yacht owners. Mashta Island has long been recognized as one of South Florida's most prestigious residential enclaves, offering exceptional privacy, quiet tree-lined streets, oversized waterfront estates, and immediate access to the open waters of Biscayne Bay while remaining only minutes from Brickell, Downtown Miami, Coconut Grove, Coral Gables, Miami Beach, and Miami International Airport. Very few neighborhoods offer this combination of island living, security, boating lifestyle, and proximity to the city's financial and cultural centers. The residence is currently on renovation designed to transform the property into a contemporary waterfront estate while preserving the exceptional value of its location and oversized waterfront parcel. This is substantially more than a cosmetic renovation. The project includes major improvements throughout the residence, including redesigned living spaces, upgraded electrical and plumbing systems, new HVAC equipment, impact-resistant windows and doors, premium flooring, modern architectural lighting, designer finishes, and a completely reimagined interior intended to meet today's luxury lifestyle expectations. Upon completion, the home is anticipated to offer spacious entertaining areas, beautifully appointed bedroom suites, bathrooms, an impressive chef's kitchen featuring custom cabinetry, premium appliances, elegant countertops, and thoughtfully designed indoor-outdoor living spaces that maximize the spectacular waterfront setting. The property's exceptional orientation provides beautiful water views and unforgettable sunsets while creating an ideal environment for entertaining, family gatherings, and year-round outdoor living. The expansive backyard offers generous space surrounding the swimming pool together with multiple areas for outdoor dining, lounging, and enjoying the waterfront lifestyle that has made Key Biscayne one of the most desirable residential communities in South Florida. For boating enthusiasts, few properties can offer the combination of oversized waterfront, private dockage, deep-water access, and unrestricted navigation to Biscayne Bay and the Atlantic Ocean without fixed bridges. Whether accommodating a large sport yacht, cruising yacht, center console, or multiple vessels, the waterfront configuration provides flexibility rarely available in today's market. Key Biscayne continues to be recognized as one of South Florida's most exclusive island communities, celebrated for its pristine beaches, excellent schools, private clubs, marinas, tennis facilities, parks, bicycle paths, restaurants, and relaxed coastal lifestyle. Residents enjoy the unique advantage of living within a peaceful island environment while remaining only a short drive from Miami's world-class shopping, fine dining, cultural institutions, private airports, international business centers, and professional sports venues. The supply of premium waterfront homes on Mashta Island remains extremely limited due to the neighborhood's established character and finite number of waterfront parcels. As a result, opportunities to acquire large waterfront lots with substantial dockage and direct ocean access continue to be highly sought after by both domestic and international buyers. The combination of location, waterfront dimensions, boating accessibility, oversized lot, and comprehensive renovation creates a property with exceptional long-term appeal. Showings are strictly by appointment with the Listing Agent.. All measurements, dimensions, lot size, square footage, waterfront frontage, dock dimensions, room sizes, zoning, taxes, permits, specifications, plans, renderings, and property information are believed to be accurate but are not guaranteed and should be independently verified by Buyer. Renderings, conceptual plans, floor plans, specifications, and construction updates are available upon request when applicable. This offering represents an extraordinary opportunity to secure one of Key Biscayne's waterfront residences . Whether as a primary residence, seasonal retreat, or long-term investment, this property combines one of South Florida's most desirable locations with an outstanding boating lifestyle and exceptional future value. Bring All Offers.

This single family residence home located at 631 N Mashta Drive, Key Biscayne FL 33149 is currently for sale and has been available on Brickellsold for 58 days. This property is listed at $19M. It has 4 beds, 4 bathrooms, and is 2255 square feet. It was built in 1958. 631 N Mashta Drive, Key Biscayne FL 33149 is in Key Biscayne county Miami-Dade County.

Interior

Bedrooms
4
Bathrooms Full
4
Features
  • Flooring: Concrete, Tile
  • Common walls with other units/homes:
Heating
Central, Electric
Cooling
Central Air
Appliances
Electric Water Heater, Dishwasher, Dryer, Free-Standing Freezer, Microwave, Refrigerator, Self Cleaning Oven, Wall Oven, Washer
Total structure area
3,720
Total interior livable area
2,255 sqft

Property

Parking
  • Covered Spaces: 2
  • Parking Features: 2 Or More Spaces,Circular Driveway,Driveway
Parcel Number
24-52-05-008-0070
Features
  • Entry location: Entrance Foyer, Walk-In Closet(s)
  • Exterior Features:
  • Has View: Yes
  • View Description: Bay, Intracoastal View, Pool, Water, Bay View

Construction

Property subtype
Single Family Residence, Residential
Materials
Concrete Block Construction, Brick
Condition
  • Year Built: 1958

Community & HOA

Community
  • Security Features:
  • Subdivision: MASHTA ISLAND
HOA
  • Amenities: Boat Dock, Private Pool
Region
Key Biscayne

Financial

Price Per Sqft
$8,204/sqft
Taxes
$112,485/yr
On Market Date
7/28/2026
Listing Terms
All Cash, Conventional

Metadata

Added
7/30/2026
Updated
9/25/2026
MLS#
B26058354
Days on Market
58
Listed By
Coldwell Banker
Originating MLS
BeachesMLS

Map

Price History

EventPriceDate
Original list price$18,500,000Jul 30, 2026

BrickellSold Intelligence

Unlock the complete property report

See a fair-value range, recent comparable-sales analysis, building performance, estimated ownership costs, rental returns and current market leverage.

Create a free account

Explore real estate near Key Biscayne

Compare this single family residence with current Key Biscayne, FL inventory, nearby properties, local market context, and practical Miami buyer guidance. Listing prices and availability are refreshed from the MLS.