The Royal & Derngate, Looking Glass and The Deco theatres, Delapre Abbey, The Roadmender and the Lift Tower all got involved in the national #LightItInRed campaign.
The University of Northampton, Althorp House, Steffans Jewellers and Wollaston BMW were also emblazoned with red light from around 9pm.
The campaign organisers believe more backing is needed for all of the businesses and individuals who rely on arts venues, some of which remain closed after the coronavirus lockdown.
The Royal & Derngate tweeted: "Tonight we're illuminated in red in a message of hope for our sector and solidarity with all freelancers, artists, event staff and businesses who work across it. We’re standing by to reopen."
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The University of Northampton got involved in the Light It Up Red campaign. Photo: Leila Coker
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The Derngate entrance was lit up red and covered in pink tape for the similar Scene Change campaign. Photo: Leila Coker
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The Derngate entrance was covered in pink tape for the similar Scene Change campaign. Photo: Leila Coker