The soul singer serenaded the Olympics silver medallist during his BT London Live performance on Monday (August 6), after he asked her to join him on stage.
"Laura's a wonderful role model for Great Britain," Lemar told the Daily Star.
Laura Robson won silver in the mixed doubles tennis event with partner Andy Murray on Sunday (August 5), who had earlier won gold against Roger Federer in the men's singles tournament.
Lemar also spoke about his new single 'Invincible', which he hoped would coincide well with the current mood in the country.
He said: "When times are hard that message of feeling invincible when you're together is a poignant one."
His brand new single will be released on Monday, August 12.
Lemar recently released a behind-the-scenes clip for the video of the track.
Sky Sports will use 'Invincible' as the soundtrack to their golf, tennis and football adverts.
The former Fame Academy star's fifth studio album, will be released later this year.
Watch the video for Lemar's 'Invincible' below: