The Scot was already assured of at least a silver in the men's singles when he tackles Roger Federer in a rematch of their Wimbledon encounter last month.
This afternoon, he and Robson saw off German and Australian opposition to reach the mixed doubles final.
Robson was the last member of Team GB to enter the Olympics after the last-minute withdrawal of Croatia’s Petra Martic because of a foot injury.
In the semi-final, Germany's Sabine Lisicki and Christopher Kas clawed back from a set and 4-2 down to take the second set and force a champions' tie-break.
But a combination of classic Murray shots, and Robson conquering some nerves to maintain her serve, allowed the British duo to advance 10-7.
Earlier, they had managed an unexpected victory over Australian opponents, beating Lleyton Hewitt and Samantha Stosur 6-3 3-6 10-8.
The pair looked confident in the opening set but Hewitt and Stosur, both grand slam singles champions, showed their class to level the match.
The first point of the match tie-break had to be replayed as a ball girl mistakenly ran across the court when she wrongly thought the point had finished.
It looked as though victory might slip away from the British pair, with men's singles finalist Murray letting out a howl of frustration as he and Robson slipped 7-5 down in the tie-break. But they pulled it back to secure a place in the semi-final against the Germans.
In the singles, Murray hopes taking Roger Federer into new territory can help him achieve a different result when he goes for Olympic gold.
The match takes place exactly four weeks after Federer ended Murray's hopes of a first grand slam title on Wimbledon's Centre Court and left the Scot distraught.
Murray has bounced back superbly from that disappointment and yesterday produced one of the best performances and results of his career to beat Novak Djokovic 7-5 7-5 in the semi-finals in front of a raucous and partisan crowd.
It will be a first Olympic final for Murray, and perhaps surprisingly a first singles final for Federer, who won men's doubles gold with Stanislas Wawrinka in Beijing four years ago.
Murray said: "I don't think going into a match thinking about revenge for something that's happened in the past really helps. I need to focus on the future.
"The one thing I hope on Sunday, he's not played for the gold medal in singles before and most times when I've played him he's experienced the situations way more times than me.
"He's played eight Wimbledon finals and it was my first one. It's so rare for him to be in a position where he's trying to do something new.
"I hope that will even things out a bit but it's going to be a tough match, obviously, and I'll need to play great tennis to win. I hope it's a great match because I think the way the matches went today, the tournament deserves a great final."
Federer has never won an Olympic singles medal but he guaranteed that will change this year by edging out Juan Martin Del Potro 3-6 7-6 (7/5) 19-17 in a remarkable contest.
Among the motivating factors for Murray was his failure in Beijing, where he lost in the first round, and he is thrilled he will contribute to Great Britain's medal haul, but he is not finished just yet.
The Scot said: "Coming into the semi-finals, when you have Djokovic, Roger, Del Potro, there was definitely no guarantees of winning one (a medal), so to get through and do that is great. That's what I wanted to try to achieve before the tournament started.
"But now I'm in the final, I've got a chance to win a gold medal, and I won't have that chance again for at least four years so I'll give it everything I can to try to do that."
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