Joshua Jackson with Lupita Nyong'o and Friends at Janelle Monáe Concert Amid Divorce

Joshua Jackson's not sulking at home because his wife filed for divorce -- in fact, it's quite the opposite, because he's out on the town with Lupita Nyong'o.

The "Dawson's Creek" star went out with the actress and a group of friends Wednesday night, hitting up the Janelle Monáe concert at the YouTube Theater in Inglewood, CA.

Sources with direct knowledge tell us Joshua and Lupita arrived together, but were among a group of about 9 or 10 people ... they've known each other for years, and there's nothing romantic about the night out.

As further proof, we're told there was no PDA, and Lupita's recently been linked to Selema Masekela ... though it appears she recently removed all traces of him on her Instagram, so there's a chance they're no more.

As for Joshua, TMZ broke the story ... British actress/model Jodie Turner-Smith pulled the plug on their marriage earlier this month, filing for divorce after 4 years of marriage.

Since the split, Jodie's been showing off her post-breakup hotness at a couple fashion shows over in Europe.