A small hamlet existed before the completion of the abbey in 1128 but the settlement started to flourish with the arrival of the monks.

In Roxburgh Street is the outline of a horseshoe petrosomatoglyph where the horse of Charles Edward Stuart cast a shoe as he was riding it through the town on his way to Carlisle in 1745.

[6] For some period of time, the Kelso parish was able to levy a tax of two pennies Scots on every Scottish pint of ale, beer or porter sold within the town.

Every year in July, the town celebrates the border tradition of Common Riding, known as Kelso Civic Week.

The festival lasts a full week and is headed by the Kelsae Laddie with his Right and Left Hand Men.

The Laddie and his followers visit neighbouring villages on horseback with the climax being the Yetholm Ride on the Saturday.

The festivities include dancing, street entertainers, live music, stalls and a free concert.

Sir Walter Scott attended Kelso Grammar School in 1783 and he said of the town: "it is the most beautiful if not the most romantic village in Scotland".

Another attraction is the Cobby Riverside Walk which goes from the town centre to Floors Castle along the banks of the Tweed passing the point where it is joined by the River Teviot.

Famous people from Kelso have included the suffragette Georgiana Solomon who was born here in 1844, the civil engineer Sir James Brunlees (1816–1892) who constructed many railways in the United Kingdom as well as designing the docks at Avonmouth and Whitehaven.

Sir William Fairbairn (1789–1874) was another engineer who built the first iron hulled steamship the Lord Dundas and constructed over 1,000 bridges using the tubular steel method which he pioneered.

Thomas Pringle the writer, poet and abolitionist, was born at nearby Blakelaw, a 500-acre (2.0 km2) farmstead four miles (6 km) to the south of the town where his father was the tenant.

Donald Farmer, a Victoria Cross recipient was born in Kelso, as was Ross Ford, who holds the record for the most senior caps (110) with the men's Scotland national rugby union team.