Walking bass is a technique used by bass players in jazz music. Most notes of a walking bass line have the duration of 1 quarter note. The function of a walking bass is to outline the harmony and keep the time together.
While walking bass in a combo is usually played by the bass player it also comes in handy for guitarists in a solo or duo situation. The difficulty lies in the combination of 2 things: chord accompaniment and keeping the bass going. This kind of walking bass guitar lines have to be played fingerstyle (guitar tablature below).
The first example is a walking bass line with chords for a II V I VI progression. I used shell chords because they are easier to fret in combination with the walking bass line. Play the bass notes with your thumb and the chords with the first and second finger. First learn to play the pattern error free, then try to add some variations and gradually speed up. Try to add some ghost notes as well.
Here's the fingerstyle guitar tablature:
This second example uses the same bass line, but with tensions added to the chords for a bit more color. Experiment with other top notes to get a different voice leading.
In the last example I show you this fingerstyle guitar technique applied on a standard 12 bar blues progression.
Here's the fingerstyle blues guitar tablature: