Smith was named the man of the match at the DW Stadium as he and McGillvary helped the Lions to a 20-14 win over the Kiwis.
Speaking afterwards, the England head coach singled out the duo for their displays in the decisive third Test.
"Both were tremendous," McNamara is quoted as saying by Total Rugby League.
"Jermaine was out on his feet but his effort was great and he brought to us what I felt we needed. It was another wet game and a fight for field position and Jermaine was very good at getting out of his own end. He won us penalties and play-the-balls and he managed to wrestle play back for us.
"Matty deservedly got man of the match; he controlled the game for us really well and kicked well all afternoon. He played smart and brought others into the game at the same time."
England have now won three of their last four internationals, including an 84-4 victory against France.