| Decimal | Longueuil | Information Technologies (IT) |
| Decor Experts Expo Inc | Longueuil | Tout Entreprises et services |
| Decor Trianon Ltée | Longueuil | Clothes Lines |
| Delisle, Gilles | Longueuil | Audiologists |
| Demers Quincaillerie Industrielle | Longueuil | Abrasives |
| Denis Dompierre CGA | Longueuil | Accounting Services |
| Denis Dompierre CPA M Fisc | Longueuil | Accounting Services |
| Denise Couture | Longueuil | Couture, COUTURE |
| Dermalissant - Esthétique Et Épilation Longueuil | Longueuil | Beauty & Fitness, Hairdressers & Beauty Salons |
| Dermapure Longueuil | Longueuil | Beauty & Health Spas |
Publicité (Desktop) Publicité (Mobile) |
| Descair | Longueuil | Air Conditioning Contractors |
| Deschamps Patrice | Longueuil | Dentists |
| Descôteaux Huissiers de justice | Longueuil | Bailiffs |
| Design Absolu | Longueuil | Beauty & Fitness, Hairdressers & Beauty Salons |
| Design Gilbert Hayart | Longueuil | Architects |
| Design Raynald Roy | Longueuil | Fitness Gyms |
| Desjardins de Longueuil | Longueuil | Banks |
| destilino.com | Longueuil | Tout Informatique et internet |
| Destination Niko & Joujou | Longueuil | Children's Clothing Stores |
| Dialogic Corporation | Longueuil | Information Technologies (IT), Tout Informatique et internet |
Publicité (Desktop) Publicité (Mobile) |
| Diane Beauchamp Massotherapeute | Longueuil | Massage Therapy |
| Diocèse de Saint-Jean-Longueuil | Longueuil | Tout Communautés et société |
| Diocèse Saint-Jean-Longueil | Longueuil | Churches & Other Places of Worship |
| Directo Service De Comptabilité Et De Gestion Au x Entreprises | Longueuil | Bookkeeping Software & Accounting Systems |
| Discount Car and Truck Rentals | Longueuil | Car Rental |
| Distribution Polycrete Mntrl | Longueuil | Building Contractors |
| Distributrice Automatique Ben Inc | Longueuil | Coffee Wholesalers |
| Diva Auto Inc | Longueuil | Car Repair |
| Doigts de fées | Longueuil | Beauty & Fitness, Hairdressers & Beauty Salons |
| Dollarama | Longueuil | Tout Commerces au détail, Candles |
Publicité (Desktop) Publicité (Mobile) |
| Domaine d'Iberville Apartments | Longueuil | Apartment Rental, Apartments |
| Domaine D'Iberville Ltée | Longueuil | Apartment Rental, Apartments |
| Don Design | Longueuil | Tout Commerces au détail |
| Dotemtex | Longueuil | Tout Entreprises et services |
| Dotemtex Recherche de Cadres Inc. | Longueuil | Tout Entreprises et services |
| Dr André Nguyen | Longueuil | Dentists |
| Dr Bernard Couturier | Longueuil | Medical Clinics |
| Dr Dominic Beauchemin | Longueuil | Chiropractors |
| Dr François Auger | Longueuil | Chiropractors |
| Dr Jean-Yves Sirois | Longueuil | Dentists |
Publicité (Desktop) Publicité (Mobile) |
| Dr Rejean Begin | Longueuil | Medical Clinics |
| Dr. Lussier-Morin Annie-Claude | Longueuil | Dentists |
| Dr. Saife Muhsin Dmd | Longueuil | Dentists |
| Dre Mélie Lavigueur Lachance | Longueuil | Dentists |
| Drenlia Inc. | Longueuil | Computer & Technology Assistance Programs |
| Dubé & Tétreault CPA S E N C R L | Longueuil | Bookkeeping |
| Duong Thong Pharmacien | Longueuil | Pharmacy |
| Duoson Multimedia Inc | Longueuil | Audiovisual Equipment & Supplies, Audiovisual Equipment & Supplies Rental |
| Duvet Etc | Longueuil | Bedding & Linens |
| Dynastie Royale | Longueuil | Beauty & Fitness, Hairdressers & Beauty Salons |
