Here are highly regarded boutique hotels across Sri Lanka that offer on-site spa or wellness services (grouped by region). I’ve included a short note about each property’s spa/highlight and a source you can open for details and booking.

South coast / Bentota / Galle region

• Saman Villas — Bentota: Classic Sri Lankan boutique (27 suites) with an on-site spa, sauna, hot tub and private-pool villas—good for a tranquil seaside stay. (en.wikipedia.org)
• Amanwella — Tangalle: Luxury boutique resort on the south coast with Ayurvedic-inspired massages and treatments (in-suite or on the beach), yoga and a long pool overlooking the sea. (Aman.com)
• The Fortress Resort & Spa — Koggala (near Galle): Boutique-luxury resort with a dedicated spa, several dining options and beach access—well suited for couples and surf/sea travel. (en.wikipedia.org)
• Haritha Villas + Spa — Hikkaduwa area: Smaller villa-style property with spa and wellness offerings in the Hikkaduwa/Thiranagama area. (en.wikipedia.org)

Hill country / Central Sri Lanka

• Santani Wellness Resort & Spa — near Kandy: A recognised destination spa and boutique retreat focused on Ayurveda, personalised wellness programmes, hydrotherapy, sauna/steam and daily yoga; excellent for a wellness-focused stay. (santani.com)
• Jim’s Farm Villas — central hills (between Kandy & Dambulla): Boutique eco-farm villas offering Ayurvedic spa treatments and yoga in a rural highland setting. (upgradedpoints.com)
• The Manor House (Nugawela/Mansion) — Kandy area: Intimate boutique property (historic walauwa) offering relaxed, heritage-style stays with spa/massage options nearby. (en.wikipedia.org)

Colombo / Urban boutique options

• A selection of smaller boutique hotels and city spas in Colombo (Colombo 3/Colombo 7 areas) offer in-house treatment rooms or partnerships with nearby spa complexes—useful if you need a short city stay with spa access. (Check individual Colombo boutique properties for current spa services and openings). (thetimes.co.uk)

Notes and tips

• “Boutique” in Sri Lanka ranges from very small heritage houses (10–30 rooms) to small luxury resorts (40–50 rooms) — spa facilities vary from single-treatment rooms to full destination-spa centres (e.g., Santani). If you want a full wellness programme (daily treatments, hydrotherapy, medical/Ayurvedic consultation), Santani and Amanwella are standout choices. (santani.com)
• If you tell me the region you’ll be visiting (Colombo, south coast, Galle, Kandy/hill country, or east coast), your travel dates, and your budget (mid-range vs luxury), I can narrow this to 3–5 best options with up-to-date rates, availability and direct booking pages. (I can look those up now if you’d like.)

Would you like me to pull current rates/availability for any of these properties or recommend the best options by region and travel dates?