After eight years with the Scarlets, he moved to England to play for Bath in the English Premiership, where he spent six seasons before returning to Wales with Cardiff Rugby.

[11] After being an unused replacement for the 26–19 loss to England in the opening match,[12] Priestland made his international debut on 12 February 2011, making a four-minute cameo at full-back in a 24–6 win over Scotland at Murrayfield.

[19] Having seemingly done enough to earn a place in Warren Gatland's World Cup squad, Priestland was left out of the final warm-up match against Argentina.

[21] With Jones still struggling with a calf injury, Priestland was named as Wales' starting fly-half for their opening match against reigning champions South Africa.

[22] With South Africa leading by a point with 10 minutes to go, Priestland had the opportunity to win the match with a drop goal in front of the posts, but he hooked it wide.

[26] Having seemingly won the fly-half battle, Priestland again started against Ireland in the quarter-finals, converting two of Wales' three tries in a 22–10 win,[27] only to suffer a shoulder injury in the last two minutes that meant he missed the semi-final against France.

[30] Priestland returned to fitness in time to play in Wales' friendly match against Australia on 3 December 2011, starting ahead of Ospreys fly-half Dan Biggar.

[36] In addition, he suffered a torn Achilles tendon in a match for the Scarlets in early December 2012, ruling him out of Wales' Six Nations title defence in 2013.

A knee injury suffered in the Scarlets' final game of the 2013–14 season meant Priestland again missed Wales' summer tour to South Africa in 2014.

With Biggar now established as Wales' first-choice fly-half, Priestland was named among the substitutes for every match in the 2015 Six Nations, coming on just twice, against France and Italy, and playing a total of just 16 minutes of rugby.

[47] Biggar returned to start the remaining three pool matches, as well as the quarter-final loss to South Africa, but Priestland appeared off the bench each time.

[60] With Priestland having to compete with the likes of George North, Jamie Roberts and his Bath teammate Taulupe Faletau for those places, he was left out of the Wales squad for the 2016 Autumn internationals.

[67][68] Wales' next match against South Africa was on 2 December, outside the World Rugby international window, which meant Priestland was unavailable as he had to return to his club side.

[74] In January 2022, he was named in the Wales squad for the 2022 Six Nations Championship;[75] however, he suffered a calf injury early in training for the tournament,[76] and on 1 March 2022, he was released back to his club for treatment.