The Doctor Who star was first reported to have broken up with Lowe in November, with a source suggesting that the split was down to their conflicting work schedules.
However, an insider claimed earlier this year that "it would be wrong to assume their relationship is over for ever".
The pair have now been spotted getting cosy backstage at the Hackney Weekend festival in London, according to The Sun.
"Matt was trying to disguise himself by wearing his hood up as he hobnobbed backstage, but when Daisy came over he didn't seem to care who was watching," a source revealed.
"His eyes just lit up and they were locked into deep conversation - hugging each other all the time.
"At one point he gave her bum a big squeeze. If they're not together any more then they have a funny way of showing it."
A friend also told the paper: "Matt adores Daisy. He has been obsessed with her for years, so it's no surprise that he's still in love with her."
Smith is currently filming the seventh series of Doctor Who, and has assured fans that he will be involved in the show for the "foreseeable future".
> Daisy Lowe: 'You can always judge a man by his shoes'
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Watch a trailer for the upcoming series of Doctor Who below: