Masandawana were without Denis Onyango and captain Hlompho Kekana, but welcomed back Gaston Sirino and Thapelo Morena from the win over AmaZulu on Wednesday evening.
Sundowns went ahead as early as the sixth minute after Sirino played an inch-perfect ball for Mauricio Affonso, who needed no second invitation to nod home.
The two sides squared up for the first time ever, with the Angolans embarking on a continental debut as the Brazilians looked for a fine start to the group.
Momentum piled up for the Brazilians and Motjeka Madisha was at the end of Tebogo Langerman's cross to nod into the far post of the net a minute before the half-hour mark to double Sundowns' advantage.
Sundowns lost their opening group stage game last year to Nigeria's Lobi Stars away but with the balance of the match in their favour, there appeared no sign of that happening again.
Masandawana head coach Pitso Mosimane put on his first substitution towards the last 20 minutes when Lebohang Maboe made way for Lyle Lakay in the final third of the field.
Lakay wasted no time and drove right into action when he delivered a telling cross to Affonso, who headed against the top of the crossbar within four minutes.
With 14 minutes remaining, Sphelele Mkhulise opened his continental account after calmly finishing off Sirino's excellent through ball to give the hosts a healthy three-goal lead.
The healthy lead remained intact as Masandawana claimed all the points to top Group C after the first round of matches.
Sundowns: Mweene, Morena, Langerman, Madisha, Arendse, Jali, Coetzee, Maboe, Mkhulise, Sirino, Affonso.
Subs: Pieterse, Soumahoro, Makgalwa, Mabunda,Lakay, Vilakazi, Ngcongca.