Montgomery was initially inspired by the graffiti artists of East London, the poetry of Philip Larkin, the philosophy of Guy Debord, and the French student protesters of May 1968. Montgomery became interested in the Situationist tradition while following the writing of Roland Barthes and Jean Baudrillard during his time at Edinburgh College of Art. Montgomery also cites lyricists as important influencers, as his poems often mirror the tone and structure commonly used by song Writers. He often writes with a certain melancholy, stating that he is fascinated by the sentiment as the creation of beauty from sadness. Montgomery describes his process as being random and unpredictable: "You quite often get stuff at like 2 o'clock in the morning and kind of see what you've got. I quite like that process". In selecting a platform for his art, Montgomery was inspired by Jenny Holzer and Felix Gonzalez-Torres' use of billboard space.

Robert Montgomery was born in 1972 in the village of Chapelhall, Scotland, to David and Janette Montgomery.

From 1995 to 1997, Montgomery was the Core Program Artist in Residence at the Museum of Fine Arts in Houston Texas.

In 1999, Montgomery moved to London in 1999, where he worded for the magazine Dazed & Confused.

One of his most famous and personal light pieces, People You Love, was written as a result of the sudden death of a close friend from art school called Sean Watson who died as a result of being hit by a car on the Edgware Road in 2004. This was the first real experience of grief Montgomery had felt in his adult life, hitting him badly. One night he had a dream that Watson was there and alive, when he woke up the following morning he says that he woke up happier than he'd gone to bed, which led him to thinking that "maybe this is what ghosts are, maybe ghosts are a positive thing."

Montgomery showed at the 2011 Venice Biennale and was selected to represent the UK at the first biennale in India - The Kochi-Muziris Biennale – in December 2012. He has also had solo exhibitions at venues in Europe and in Asia, including major outdoor light installations on the site of the old US Air Force base at Tempelhof. The first monograph of his work was published by Distanz, Berlin in 2015.

Robert Montgomery's Echos of Voices in the High Towers was published by Mono Kultur in 2012. The Book is A2 in size, folding out to A1 in size, divided into three parts, and serves as a complete publication of Montgomery's work.

in 2016, Montgomery and his partner, Greta Bellamacina, launched their own publishing company called New River Press, dedicated to pushing the boundaries of what poetry means today particularly for a younger audience "we want to launch a place for poetry that doesn't exist yet."

After being in a long-term relationship with frequent collaborator and fellow poet Greta Bellamacina, the two married in July 2017. To celebrate Montgomery created a wedding fire poem which read, "SALVAGE PARADISE. LOVE IS THE WEATHER. DAYDREAMS FOREVER" before being set alight. Likewise, Bellamacina wrote him a fire poem reading "ETERNAL WINDOW HYMNS". The two met when Bellamacina was editing a book of love poetry and put one of Montgomery's poems in the book. She later said that "it was refreshing to meet someone through their words, you can find out a lot about the person." In 2015, Bellamacina gave birth to their first child, a son, Lorca.